So that is the plug for one of the washer pumps. There are two. I initially just cut off the tabs and painted mine black. However, in colder climates the washer fluid would freeze. Yes, I know they make fluid that can go to colder climates but good luck finding it in CA. So, during their Xmas or Black Friday sale I picked up a Rocksteady Washer Kit on sale. It isn't cheap hence why I jumped on the sale, but it is nice! And my fluid didn't freeze when I was up in OR in the snow so I was super happy. It's a great piece with detailed instructions and would highly recommend. I just sprayed it with truck bed liner but you can get it powder coated if you like.