Cx Lenses are first generation EnChroma lenses and are made of Trivex, whereas the next generation (i.e Outdoor Deutan, Outdoor Protan and Indoor Universal) are made of Polycarbonate. EnChroma's next generation of lenses design delivers up to 35% better color performance, renders whites and neutrals more accurately, but both generations of lenses are scientifically proven to stimulate your brain’s color vision processing. The naming system for Cx refers to the overall lens categorization that is standard in the lens industry to indicate the amount of light that is transmitted or filtered through the lens. Cx1 lenses are Category 1 filters (44-80% transmission) for indoor, lower lighting conditions and Cx3 lenses are Category 3 filters (9-18% transmission), typical for sunglasses and bright sun.