Pls note that PMMA is not only used for sunglass lens, we adopt German optical grade PMMA material to make PMMA RX optical lenses. Index = 1.49, Low specific gravity (1.19), High Transmission (93%), Anti-scratch, impact- resistant, UV-proof (400), Super Hard (105 8H), Abbe 59, Central thickness 1.0 ~ 1.5 mm. PMMA lens has better durability and long useful life. Retarding the myopia development of youngsters. PMMA lens can be hard coated or AR coated. PMMA lens cheaper than PC lenses.