There are three different material that usually apply in spectacles, glass, CR-39 resin and polycarbonate(PC).According to European and American standard, the most common and good performance matrial in safety spectacles is Polycarbonate. PC lens ks known as impact resistant, anti-scratch, UV protection, light weight and economic price. It is very dangerous to use Acrylic or plastic material as safety spectacle. Acrylic cound not against scratch, impact and UVA radiation. Moreove, it is easy become deformed. And it will result in missing focus.