Im sure i've mentioned it before, but this stuff is an absolute must for protecting plastic lamps if you do not want them to turn yellow or hazy over time. basically its like a wax for plastics that lasts months instead of days. it blocks out UV rays and prevents costly damage to the lenses. its best to use this product on new lenses before they get a chance to turn bad. just wipe it on like wax, let it haze, then wipe it off with a microfiber towel. great for headlamps, taillamps, sidemerkers, anything plastic on the outside of the car. it also has the added benefit of beading water when driving in the rain, which reduces headlight glare to other drivers and gives you more light on the road. similar to those glass treatments you put on the windshield to see better in the rain without wipers. ths stuff is expensive at $40 for a 16 oz bottle, but i usually only use one bottle every few years. this stuff is also very good at cleaning butyl off the lenses if you accidentally get some stuck while sealing up a retro. literally melts it right off without scratching.