Durable lightweight / polycarbonate open close board Polycarbonate is a kind of plastic, but it has an impact resistance of over 200 times more than ordinary glass, and is a very strong material that will not break even if hammed with a hammer. The material is easy to handle because it has strong impact resistance that makes it soft to the stomach. It is also used in airplane and bullet train windows where strength and safety are required, as well as bulletproof shields held by special forces.