Todays cars have a composite headlight made from plastic that take a seperate bulb, unlike older cars that had a sealed beam, which got changed every time it went out. Todays headlights usually stay in the vehicle for the life of the vehicle, and over time they yellow, chip from stones, and are put under intense heat from the bulb and from the sun, which will fade them, or in some cases, peel the protective clearcoat from them and leave them exposed for further damage. Replacement headlights can be very costly, potentially costing hundreds of dollars to replace. Another option is restoring your headlights. We use different stages of sandpaper from Meguiars and 3M (parent company of Meguiars) (different stages of sandpaper depends on how bad the headlights are), use a buffer wheel with plastic polish from Meguiars, and protectant to help keep the headlights from further damage. This procedure could save you hundreds, plus make it safer for you at night. People dont realize how much visiblity is lost over time due to faded and yellowed headlights. Not only that, it also helps the overall apperance of your vehicle, and increase its resale value.