**** I'm adding to this per requests**** (I did mine in my heated shop @ 70 degrees,temps to applying this matters to how well it will stick) *Sanding is optional if you want. 1500 grit for the rockers just to ruff it up. *As far as the bumpers are concerned you are supposed to take 60 grit and sand them and rough them up.(*Clean them areas up with acetone.) I didnt sand either.....I choose to do Self-Etching primer insted. Then went over it with Black primer. 3 coats of each. Then 3-4 coats of the Rustoleum Bed Liner. It's easy and cheap to touch up if you have to in the future. * I did not remove the bumpers to do this but you can. I feel like it's a waste of time to do so. *This is just the option I choose(not sanding)* if you want to make sure it will stick you SHOULD sand every area good. if yours falls off from not sanding I don't want to be held responsible