Another idea about how to finish these rails, paint , bedliner , or what ? Remember, this is what I would do, only what I would do and not necessarily what Jon may recommend. The rails will be shipped in bare metal unless you have Jon powder coat them. First thing is to clean them with a de-greaser, wax and grease remover, paint thinner works fine. Then sand the metal a little . Use a scotch brite pad or some 400 grit paper. Its not going to be too critical because they are to be etched anyway for adhesion. Basically with sanding youre getting them nice and smooth and making sure there is no welding slag that was missed. ( sorry Jon ) Next, the bare metal will need to be Etch Primed. You can buy etch primer in spray can. I use DuPont brand but all brands are basically the same. After etch priming them I would use a rock guard spray, similar to what some car manufacturers use . I use a brand called TranStar. It comes in spray can also. This stuff seems to get harder than your spray can bed liner material and its probably cheaper and easier to touch up. One can will easily do two rocker panels but maybe take 2 cans to do the rails real well. It will take a couple of coats. After the rock guard I would use a satin sheen black spray paint. You can touch up this process easily and quickly. You will be scratching the sliders up on the trails and you wont have to re-do the whole slider just to touch up one spot either. I would do the rockers also before you mount the rails. Simply sand the rockers with a scotch brite pad. The red pads are 400 grit or you could use sand paper. If you simply want to paint the rockers without the rock guard, use 400 grit paper. If you want to use rock guard on the rockers then you can use 220 grit to 400 grit paper. You Do Not use etch primer on the rockers because they are already painted. Etch primer is only for bare metal. Since I work in a body shop I have the ability to paint the rails with automotive paint and clearcoat. I wouldn't recommend this because , 1- you wouldnt be able to do it in your shop very easily, 2- it is expensive, and 3- it is not easy to touch it up. Spray paint is where its at.