Each lens is casted from Trivex, a material used in helicopter windshields with the REACTIV photochromic technology sandwiched in the middle. That means the optical quality is nearly as good as glass and far superior to the polycarbonate lenses that most other brands use. It’s also why our REACTIV photochromic technology isn't temperature sensitive, and never wears off, meaning we can back our lenses with a lifetime warranty.