Lasfit Switchback Rock Lights Kit (and general Rock Light Overview)

[PJSnow]

TLDR: Rock lights can be used for much more than just illuminating rocks. Follow this thread to see how the Lasfit rock lights perform. (Scroll to the bottom of this post for photos)

General Rock Light Information/Overview

Rock lights, as their name implies, were originally created to light up the rocks under the vehicle while off-roading. I wasn't able to find any articles about their history, but I assume they are a derivative of under-glow, which was invented in 1987. Unlike under-glow that went out of style in the early 2000s, rock lights have gained traction in the off-roading community, especially over the past few years.

Rock lights are small, flat lights that are typically installed in the wheel wells above the tire. They illuminate the wheel arches and the road/rocks directly below the vehicle. Most are just a single LED or a group of LEDs in a housing without specific optics while some include a diffuser lens (I won't get into the optics of lighting in this post but diffusers spread light more evenly with a slight reduction to the overall output/brightness. A completely clear lens just allows light to pass through virtually unimpacted and scatters it predominantly in a forward direction). The standard light color for rock lights is white but there are versions that come in amber or even RGB (multi-color).

Lighting up rocks below the vehicle doesn't have to be the only use for rock lights. Many have used them for other purposes including courtesy lights, additional interior lighting, scene/camp lighting, and even for style, just as under-glow was once used (a big reason RGB rock lights are available).

One thing to note is the legality of rock lights. Some states allow the use of rock lights while driving on public roads, but most do not. Here in NY, we are allowed to use white colored lights (that do not strobe/flash) while on public roads. Any other color or even white lights that strobe are not allowed in NY (Do you mean not allowed?). Most manufacturers indicate off-road use only for their rock lights.

And finally, who makes rock lights? Most off road manufacturers sell rock lights and you can even find very cheap ones on Amazon. Some offer full kits with multiple lights and a wiring harness, while others sell individual rock light pods with a short wire pigtail, which requires the customer to complete their own wiring.

Lasfit has been expanding their off road lighting offerings over the past few years. They have made quite the name for themselves and recently released their own set of rock lights with a few unique features. When asked to test out their new rock light kit, I eagerly agreed. Based on my previous experience with their products, I had high hopes for this new kit.


Lasfit Switchback Rock Lights Kit

I don't do any rock crawling, but as mentioned above, rock lights are not only for illuminating rocks. For some reason, the TRD Pro does not come with puddle lights in the side mirrors and the courtesy lights in the doors are virtually useless (especially with a lifted truck). When asked to test the Lasfit rock lights, I immediately wanted to use them to provide more light around the doors as courtesy lights. And I would be lying if I said they don't look cool!

Lasfit offers two options for their rock light kit: one with 4 lights, and one with 8 lights. I expect they will make individual lights available in the future to add onto the 4 light kit. Here is a link to the kit:
Lasfit Off-Road Switchback LED Rock Lights Kit White & Amber

A few notes and special features about the Lasfit kit:
1. "Switchback" - The lights are dual color to allow the use of white or amber light. Although I disagree with the "switchback" nomenclature (typically used to describe turn signal bulbs), the feature is unique. This would definitely be useful for those who want a less harsh light, especially while navigating those technical trails at night, where sometimes white light is too intense for the situation.
2. Wiring Harness Included - While some manufacturers only offer individual rock lights, Lasfit includes a harness to make installation even easier. The harness includes a two-way switch to go between the white and amber light, and 8 leads to connect up to 8 rock lights to a single harness.
3. Price - I believe the Lasfit kit provides the best value considering quality and price (currently at $120 for the 4 pod kit). There are cheaper kits on Amazon, but their quality is probably questionable and I would not expect them to be reliable. On the other hand, there are big name off road brands offering individual rock light pods for $70/pod (look up Baja Designs rock lights). While I'm sure the quality is comparable, the value is not.

I opted for the 8 pod kit to allow me to illuminate the areas around the doors and to add lights under the front and rear of the vehicle primarily for aesthetic reasons. They were shipped via USPS and the packaging was top notch, on par with the packaging for other Lasfit products. The 8 pod kit came as two individual 4 pod kits, including two wiring harnesses, and each pod was individually packaged to keep them from banging together. The kit includes the pods with rubber "feet", wiring harness, mounting hardware (Allen head bolts, washers, and nuts), Allen wrench/key, zip ties, and an instruction manual.

Upon receiving the kit, I was immediately impressed with the build quality of the pods, they have a metal housing with some weight to them. The wiring harness is also very nice, it has screw-together wire connectors and the battery wires are braided and wax coated. Overall, this initial unboxing met my expectations.

Although I like this kit, there are a few points to note that might not work for everyone:
1. Not RGB multi color - For those looking to buy rock lights purely for aesthetic purposes, multi color options might be a necessity. The Lasfit kit might not be right for those buyers, but I find the white and amber to be more than adequate. The white on the RGB versions is not a pure white, which is something else to consider. The Lasfit white is a dedicated white LED chip so it is a pure white.
2. Bluetooth Connectivity - Some kits on the market offer Bluetooth connectivity to control the color of the lights (mainly the RGB versions). Lasfit only has two color options so I don't think Bluetooth is necessary. The simplicity of the kit makes for a more reliable product. Although Bluetooth is a proven technology, reliability of the system is questionable and it can malfunction. Also, most Bluetooth kits rely on your phone having a battery charge to turn them on. The Lasfit kit will work regardless of your phone's battery percentage!
3. Size - The individual rock light pods are a bit larger than other offerings but Lasfit also crammed in more LEDs compared to the competition. If you are constrained to very tight spaces, this might not be the kit for you.


Initial Impressions/Review

I installed the kit a few days ago and have been happy with it so far. Everything seems to work as intended and it certainly looks the part. The white light is crisp and bright under the 4Runner.

I have yet to figure out a wiring solution to have the lights turn on when I open a door, but for now, the included switch will have to do. While on the topic of the switch, I have to say it is very basic. It is a universal round two-way switch that stands out in the 4runner interior. Some may choose to cut a hole to mount it through an interior panel but I like a more factory aesthetic. I will likely try to find an OEM style two way switch to replace it with.
I am eager to see how these perform after a rain storm and after driving through dust or mud. I am curious to see how they hold up to moisture (condensation build up) and if my mounting locations are prone to dirt build up. These are more long term criteria that I'll report back on. But so far, there are no complaints.

I will discuss my specific installation in the next post if anyone wants to do the same, but I want to note a few things I noticed:
1. The hardware provided is a bit short, especially when using the supplied rubber feet. They are only really meant for thin sheet metal or use without the rubber feet. You may need to purchase longer bolts if you mount through thick body panels or the frame.
2. This is a universal kit intended to work with a multitude of off road vehicles. I found the length of harness for the rear light pods to be barely long enough for my application. For anyone with a longer vehicle (for example a long bed Tacoma), the harness may not reach the rear of the vehicle. I'm sure you can cut and splice in to add length, but it would be nice if Lasfit made an add-on extension harness for those who need it.
3. The rubber feet are contoured for a round surface. I'm sure they work great if mounting to a tube (example aftermarket sliders) or a round body panel, but most surfaces on the underside of the 4Runner are flat (example: the frame and wheel arches). I wish they provided flat rubber feet as an alternative.

Overall, the value of this rock light kit seems unmatched. I would definitely recommend this kit if it fits your build. Lasfit has been doing a great job with their off-road products and is certainly making a name for themselves. I am eager to see what else they have in the pipeline for their off-road line!


Photos

And now for some glamour shots.

This is the amber color:

Here is the white color:

This photo shows the spread of the rock lights. They do well as courtesy/puddle lights, I just need to wire them up to the doors.

Here you can see the amber color compared to my yellow Diode Dynamics fog lights. The Lasfit color is definitely a true amber color.

The spread of the white and amber lights are identical:

This shot gives a nice color comparison to my Lasfit Pro headlights:

Here you can see the flaw in mounting the rear lights in different positions. I will likely change something in the future but not sure on my plan yet.

And one last side profile:

 

[mrblah]

Nice review.

Since, i rarely wheel at night, I am tempted to get these and use them on my roof rack as camp lights.

 

[PJSnow]

Installation

Now, onto installation. I decided to install my kit with zip ties because I didn’t want to cut holes in my 4Runner. I also plan to test a few different locations for mounting the lights and zip ties make removal easier.

Most choose to mount rock lights in the wheel wells, but I think all that does is light up the top of the tires. This location doesn’t illuminate the ground or rocks/obstacles below the vehicle. There are also no mounting holes in the rear wheel wells and I have no intention of drilling holes into my 4Runner. Unlike most, I still have running boards (primarily for the vertically challenged family members) and I decided to mount 4 pods on the undersides of them. The other 4 pods I decided to mount under the front radiator support and adjacent to the spare tire. I might play around with mounting locations in the future, but for now these points worked best for me.

Total installation time, including a lunch break, was about 5-6 hours. Most of that time was deciding on mounting locations and routing the wires. The most difficult part was passing the switch wires through the firewall (always seems to be a challenge for me…).

Here is a photo guide on how I completed my installation:
1. I started by mocking up the pods under the running board since this was my primary purpose for the rock lights. I decided to mount one at the front of the running board without the rubber foot. It fits nicely and there are already two holes that accept the zip ties. The harness easily feeds above the body mount and can continue straight up into the engine bay. Mounting on the driver and passenger sides are identical. Here are photos of my specific running boards and where I mounted the front pods:

2. Next, I mounted the pod at the rear of the running board. The holes I used at the front are taken by some sort of mud guard or aero piece at the rear. There are holes along the length of the underside of the running board but drilled a single small hole to pass the second end of the zip tie through (this is a small hole through aluminum so I am not concerned about corrosion or structural integrity). Both the driver and passenger sides mounted the same. I routed the harness around the running board leg/bracket and zip tied it to the parking brake cable on both sides. Once over the frame, I then zip tied the harness to an existing factory harness on the passenger side and to the brake lines on the driver side. These both run up into the engine bay to meet the other harnesses. Here are photos of where I mounted the pods at the rear of the running boards and how I routed the harness on each side:

3. Once the main rock lights were installed, I decided to move to the rear of the 4Runner. As mentioned earlier, the rear wheel wells do not have any holes or opportunities to mount the rock lights without drilling into the body. Mounting at the top of the wheel well only illuminates the top of the tire. I decided to mount mine farther back around the spare tire. On the driver side, I used two existing holes in the bottom of the frame. On the passenger side, the factory exhaust (non TRD Pro) runs directly under the frame rail and would block the light. I decided to mount the light on the spare tire brace(?) on the passenger side. It angles up but I was able to shove a rubber block between the light and the metal brace to angle the light downwards. Overall, this is the location I am least pleased with and may change in the future. Once mounted, the harnesses run up and over the frame before merging with the harness from the rear of the running board. I found it easiest to pass the harness over the frame and into the wheel well (easier to pass the harness forward while staying above the frame). Here are a few photos of the rear mounting location:

4. Once the 6 pod harnesses (3 from each side) are routed up to the backside of the front tires, I ran them up into the engine bay. I found it easiest to remove the rubber splash guards to see clearly. On the passenger side, I continued to follow the factory harness that runs up into the engine bay. On the driver side, I continued to follow the brake lines to lead into the brake booster. Once in the engine bay, I temporarily tied the 6 harnesses to keep them in place using a twist tie. Here are a few photos:

5. Lastly, I moved to the front. Again, I didn't want to mount these in the wheel well so I looked for locations in front of the front wheels. The only place that seemed to work is the factory tie down points (arguably recovery points?) under the radiator support. I have a set of aftermarket recovery points so I was not concerned about covering these. The zip ties looped nicely through the tie down points and the harness can be fed up into the engine bay around the radiator. On the driver's side, the harness pops out in front of the battery and can be run along the fender for a hidden look. On the passenger side, I decided to run the harness under the intake tube because the intake box sucks air from the fender (no clearance to pass the harness between the fender and the intake box. Once the front pod harness was at the rear of the engine bay, they met up with the other harnesses that were brought up (see point 4 above). Here are a few photos of the front mounting:

6. After all the light pods are mounted and the individual harnesses are run into the engine bay, I then routed the main harness within the engine bay. I began by fishing the switch wiring through the fire wall using an existing grommet (this is always a pain but there are plenty of videos on Youtube to help). The wires simply disconnect from the back of the switch but it is still a chore to fit through the grommet. The power leads can then be run towards the battery (both positive and ground), which I found cleanest to feed between the fuse box and fender. I removed the inline fuse on the power wire before connecting anything to the battery as a safety precaution but this may not be necessary. Lastly, the pod connector was run to the top of the fire wall and zip tied to a factory wiring harness. I needed to mount this near the center of the engine bay to reach the individual harnesses from the rear mounting locations (this is where I wish there was a bit extra length on the pod harnesses to give flexibility on mounting, especially for longer vehicles). The individual harnesses connect to the main harness with nice weather sealed screw-style connectors. Here are a few photos of the main harness mounted:

7. And that is about it for the install! Time to enjoy your rock lights. Don't forget to take the blue film off the pods, otherwise you will have blue under glow (AMHIK).

 

[emmantik]

Great write up!

I believe DSIM Solutions has a module that allows you to have the lights turn on with the dome lights like you mentioned you were looking to do. See link.

DSIM Solutions

 

[SlickTRD]

thanks for the review.

i think you should also undercoat with fluidfilm or woolwax. do it now and touch up before weather gets very cold in the fall.

 

[PJSnow]

Great write up!

I believe DSIM Solutions has a module that allows you to have the lights turn on with the dome lights like you mentioned you were looking to do. See link.

DSIM Solutions

Very interesting! Thank you for the recommendation. Looks like they cater more to the Tacoma but I'll look more into it.

 

[PJSnow]

thanks for the review.

i think you should also undercoat with fluidfilm or woolwax. do it now and touch up before weather gets very cold in the fall.

Thanks for the recommendation. I've looked into undercoating products but they all leave an oily film that makes working under the vehicle a nightmare. I'd love to protect the 4runner but I don't want the mess (I don't need an excuse to skip maintenance and I know the oily mess will deter me from wanting to do an oil change, let alone other maintenance).

 

[emmantik]

Very interesting! Thank you for the recommendation. Looks like they cater more to the Tacoma but I'll look more into it.

Yes mostly to Tacoma's but they have options for 4Runners and a universal option FWIW. Cheers!

 

[chrisridebike8]

Nice review.

Since, i rarely wheel at night, I am tempted to get these and use them on my roof rack as camp lights.

I've been thinking of doing the same with a set of 4. The thing I don't like about most of these systems is that each pod has its own wire which makes it tough to use something like a KC wire hider to run them down the windshield. With something like the baja rock lights, I can just make my own harness that only has 2 wires to run down the windshield. I wonder how hard it would be to use these LASFIT pods and just make my own harness.

OP, when you installed these, what do the connectors look like, and how many wires does it look like run to each pod. nice review btw.

 

[mrblah]

I've been thinking of doing the same with a set of 4. The thing I don't like about most of these systems is that each pod has its own wire which makes it tough to use something like a KC wire hider to run them down the windshield. With something like the baja rock lights, I can just make my own harness that only has 2 wires to run down the windshield. I wonder how hard it would be to use these LASFIT pods and just make my own harness.

OP, when you installed these, what do the connectors look like, and how many wires does it look like run to each pod. nice review btw.

yeah id have to see the wiring schematics. Maybe the OP can post the pic diagram if it was included in the box.

 

[PJSnow]

I've been thinking of doing the same with a set of 4. The thing I don't like about most of these systems is that each pod has its own wire which makes it tough to use something like a KC wire hider to run them down the windshield. With something like the baja rock lights, I can just make my own harness that only has 2 wires to run down the windshield. I wonder how hard it would be to use these LASFIT pods and just make my own harness.

OP, when you installed these, what do the connectors look like, and how many wires does it look like run to each pod. nice review btw.

yeah id have to see the wiring schematics. Maybe the OP can post the pic diagram if it was included in the box.

Here is a link to the Lasfit rock light kit harness diagram (photo is also included in their product photos on the rock lights page):
https://cdn.shopify.com/s/files/1/1827/4457/products/switchbackrocklight_5_2000x.jpg?v=1677047594

You have a few options to mount lights on a roof rack:
1. Probably the easiest method is to use the Lasfit harness as is. You can run the 125.98in section up the windshield on the driver's side (it is only a single cluster instead of 8 individual leads) and I'm sure it would fit in the KC wire hider. This would be ideal because you remove excess harness slack from the engine bay and the switch wiring can be passed directly through the firewall grommet on the driver's side. The only downside is the excess/slack from the individual pods that will need to be coiled and fastened to the roof rack somewhere. I'm sure you can hide them behind the front fairing (if you are using the common aluminum roof racks). You might also be able to shorten the individual pod harnesses if you are comfortable with automotive wiring (I expect it would require chopping out a chunk from the middle of each pod harness).
2. You could also hack up the Lasfit harness for a custom solution by lengthening or shortening sections to fit your needs. It is a nicely sealed and protected harness but I'm sure someone with experience cutting and soldering wires can customize it. This is a universal wiring harness made for many different applications. I don't have a wiring diagram to understand the flow of electrons but I expect the interior switch is just a ground switch (because there is no switch illumination and there is no relay present). I expect there are three individual wires in each cable/bundle that would need lengthening/shortening when modifying the harness (one for the white lights, one for the amber, and one for the ground). If helpful, I can try to draw a wiring diagram for how I expect the harness to be laid out but I'm not sure how to confirm my speculations.

Hopefully this makes sense. I am trying to reply quickly before work. I can follow up later to clarify or cover anything I missed.

 

[Xtremluck]

Nice detailed write up. I actually like the wiring execution of their solution but I think the optics they used for their lights is pretty terrible for a rock light use case. The light output is way too focused and not spread out. Here is a shot of (6) KC Cyclones and you can see coverage area is much broader

Also I highly recommend you loom that wire you have it routed and attached to the body and frame with lots of sharp metal sitting around. A recipe for shorting out.


Sent from my iPhone using Tapatalk

 

[PJSnow]

Nice detailed write up. I actually like the wiring execution of their solution but I think the optics they used for their lights is pretty terrible for a rock light use case. The light output is way too focused and not spread out. Here is a shot of (6) KC Cyclones and you can see coverage area is much broader

Also I highly recommend you loom that wire you have it routed and attached to the body and frame with lots of sharp metal sitting around. A recipe for shorting out.


Sent from my iPhone using Tapatalk

Thanks! I tried to zip tie it every few feet but I'll see where I can add more. Not sure it warrants a loom, the rubber sleeve (casing?) is quite good.
The lights do seem to have a more focused light compared to your photo. A frosted/diffused lens would probably spread the light out a bit more, but it would also reduce the intensity. It's probably a matter of preference at that point. I wonder if the lens could be sanded to diffuse the light more?

 

[PJSnow]

Switch Update

First off, the rock lights have been working great since I installed them. It has only been a few weeks since the install but no complaints thus far. I will plan to follow up with updates as I continue to use them.

I did get annoyed at the switch that came with the kit. It is a very basic two-way switch that sticks out like a sore thumb. If you don't mind drilling a hole through the interior plastics, I'm sure the included switch will work fine but I prefer an OEM look.

Before figuring out what switches to purchase, I decided to check what the Lasfit harness wires actually do. I tested the three wires at the switch and found the Black wire provides constant power, the Yellow wire runs to the white lights, and the Red wire runs to the amber lights. Touching the black wire to the Yellow wire turns on the white lights, touching the black wire to the Red wire turns on the amber lights, and touching all three wires together turns on both amber and white lights (more on that later).

I found several OEM style dual switches from various companies including CH4x4, AOB (only the Australia site for some reason), Cali Raised, and even eBay. Unfortunately, none of the options match the factory light blue backlight color but they all seem to have the same 5 wire plug/pigtail so they should all have a similar install. They essentially work like a normal switch but have two options to transfer power (or ground), perfect to replace the switch that came with the Lasfit kit.

I decided to go the eBay route because they offered custom graphics at the cheapest price ($20 ish). I created a simple rock light graphic and added "WHITE" and "AMBER" to distinguish between the top and bottom switch. I had an issue with the eBay seller sending the switch before I approved the mockup so I am still waiting for the all capitalized WHITE and AMBER switch (see photo below) but I was able to install it and confirm proof of concept.

Here is how I wired it and how the switch functions:
1. The top and bottom wires from the switch (Blue and Green) run to the individual light colors (white and amber). On the Lasfit harness, these are the Yellow and Red wires. Since I have the top switch set to white and the bottom switch set to amber, I wired mine with the Blue from switch connected to the Yellow from the Lasfit harness and the Green from the switch connected to the Red from the Lasfit harness.
2. The second wire from the top on the switch (Red wire) is the input power. This is what sends power to the white or amber light when the switch is engaged. The Black wire from the Lasfit harness provides this constant power as noted above. I connected the Red from the switch to the Black from the Lasfit harness.
At this point, the switch works to control the rock lights but you will have no backlights at all. Best part of this switch, you can turn on both the white and amber rock lights at the same time if you engage both the top and bottom switch, something the Lasfit switch could not do because it was a rocker style switch (only one can be engaged at a time). I'll explain the remaining two wires below but you don't need them to operate the rock lights.
3. The third/middle wire on the switch (Black wire) is the ground connection. This is needed if you want the switch backlight to function. Unfortunately, it appears the backlights are not operational without the last wire connected (see #4 below). I don't see a way to have a backlight on while the switch is engaged/depressed without the headlights on. Might be a different function with different manufacturers.
4. The fourth wire on the switch (Yellow wire) is the backlight power. You can connect this to a circuit that has power while the headlights are on (for example the TAIL fuse). If you wire this up and connect the ground wire, you will have a backlight illumination when the headlights are on (even if the switch is not engaged) and a different color illumination when the switch is engaged and the headlights are on simultaneously. Unfortunately, as noted in #3, my switch has no backlight when the switch is engaged but the headlights are not on.

I have yet to wire up the backlight because I have not had the time. My next objective is figuring out how to run the rock lights when a door is open and manually from the switch. That is an advanced electrical wiring problem that I have not figured out (I'm still working on the basics of automotive wiring). Hopefully this was helpful. It definitely proves that you can use an OEM style switch with the Lasfit harness. And here are some photos:

This is what the Lasfit switch looks like and the wires that come from their harness (Red Yellow and Black):

This is the custom dual switch I got:

These are the 5 wires that come from the switch (Blue Red Black Yellow Green). The Blue wire is at the top of the switch (on the right of the photo):

These are the connections of the new switch wires to the Lasfit harness. I used crimp on connectors and wrapped them in electrical tape to prevent contact.

 

[PJSnow]

1.5 Month Update

Figured it’s time for a quick update since I installed this rock light kit about a month and a half ago. So far there have been no issues and they’ve been more useful than expected. Here are a few of my thoughts from the past month and a half:

1. Zip ties - If you didn’t read my initial post, I used zip ties for a completely reversible install without drilling holes into my 4runner. I don’t rock crawl so there is no chance at scraping them against a bolder but I have driven through some tall grass/weeds and they have held up so far with no signs of movement. If you drive predominantly on road with mild off-roading, the zip ties should hold up fine.
2. New Switch - Since installing the new OEM style switch (about two weeks after the rock light install), I’ve found myself using them much more. It is much more user friendly and I can clearly see when I have the rock lights turned on compared to the included switch. I also like that I can turn on both the white and amber lights at the same time to create a warmer tone, making these a three-color rock light.
3. Use Cases - I had originally planned to use these as puddle lights, which they have worked well for, but I have also found other great uses for them. Although I haven’t yet worked out the wiring for the doors, even using the lights with the switch has helped spot puddles in the dark. The other great use I’ve found is for backing into my driveway at night. Since the lights are so bright, they shine around the vehicle and help me see the planter border/curb when backing up. Specifically the area at the side of the 4Runner where the reverse lights don’t shine (by the rear quarter panel and rear doors). Tip for those who might not know, tilting the side mirrors down when reversing helps significantly when parking in the city or backing up next to low objects/curbs. I’m sure these rock lights would also be a great ambient light when camping but I haven’t gotten out there yet.
4. Beam Pattern - Someone had mentioned concerns with the focused beam pattern earlier in this thread but I have no complaints with the beam pattern for my particular use. I’ve actually found the lights to be bright enough to reflect off the ground to provide fair coverage around the vehicle, even with nearby street lights. For those looking for a more diffused look, I’m sure the clear lens could be sanded a bit to create a more flood-like pattern (the LEDs should be bright enough to shine through a sanded lens). But I’m sure the focused pattern is more than adequate for most use cases.

I’ll plan to follow up after several more months or sooner if anything significant comes up. For now, here are a few more photos (took some shots while down in Maryland by the ocean):

Here are the white rock lights. They match the headlight color well and look great at night.

Here are the amber rock lights. This matches the marker lights well.

Here you can also see the Lasfit Pro headlight bulb kit (see my other thread for a write up on those)

Here is the color with both amber and white turned on at the same time to produce a warmer white color. Having both on doesn't necessarily double the light output but it definitely changes the color.