... -finished photochromic and progressive lensSemi-finished photochromic and round top bifocal/flat top bifocal Mineral 1.523 Lens, CR39 sun lens, PC ... Polarized lens, 1.499 Flat top bifocal optical lensFeatures:1) Flat-top2) Finished lens:a) Diameter ... ultraviolet damage to our eyes,make our eyes safety and health.9, Anti-radiation, EMI10,easy to machining,not easy to ...