If you try the kits they sell at the store, it will look nice for 3 months or so but it actually removes the UV coating that they apply to the Polycarbonate lens when they are made, and in result the headlights will return to their yellowed state, and actually fade 3 times as fast from that point on. You can only do this so many times....If you want to do it the RIGHT way, you're going to need to reapply some sort of UV protection to the lens. Not just a wax, you're going to want to apply a 1K or 2k clearcoat to the lens after sanding the old coating off, and all the oxidation is removed. It does not yellow, and it is very smooth if you use a spray gun. I generally start at 600 or 800 grit paper, and work up to 1500 grit. That gives the coating something to bite onto, so it won't flake off after you do it. I do quite a bit of headlight restoring, and let me tell you, just do it right the first time so you don't have to keep doing them every month or two.