From my understanding, and correct me if I'm wrong, lumens isn't the best measurement for light bars. Candela measures the visible intensity from the light source, basically, how intense is the light when it falls upon your target. Lumens measure total light given off, but that's from the source. So, when you have the light mounted on top of your roof, are you more concerned with how much light is being generated at the LED, or with how much light actually hits your target? That's why you'll find many of the cheaper LED able to seem like they're roughly the same as your expensive brands (Baja, Rigid, etc). Sure, the LEDs may emit similar amounts of light, but how is it being thrown? The lenses and reflectors themselves play a huge role in light transmission, and by paying more, you're getting lenses that have higher transmission amounts. I have an engineer friend at Rigid who explained it to me, I wish I could explain it as well as he did.