Well they use H4 halogen bulbs. Huge upgrade from stock halogens. Much the same as every other h4 housing. They are coated lexan. Mine look new after years of use. No fading or scratching like early plastic lights. And my old sealed beam glass one had a rock bullseye in it. I bought mine living in Alaska with darkness all winter. I love them. Highly recommend. Think they are made in USA like all my other KC stuff too.