Promate Scuba Dive Mask, T.Blue Frame with Panoramic View Windows for Snorkel & Diving, one Size (mk399)

Promate panoramic view dive mask with purge (mk399) features patented single lens with edge-less technology on sides (three lenses,) which increases field of vision dramatically, crystal, liquid Silicone injected skirt and strap, double skirt edge comfort seal, and low volume. It also offers 2-buttom Tec buckle adjustment system not only convenient for buckle and strap adjustment but more secure and durable use. Unlike other's buckle attaching with frame, this mask attaching with skirt makes swivel function more flexible which means fits a wide range of face shapes. It is good fit for medium face seal size w4-3/4 h3 -1/2.) tempered lens is one of safety glasses. Processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering creates balanced internal stresses which cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards. The granular chunks are less likely to cause injury. Comparing with polycarbonate lens, it is usually heavier than the polycarbonate, but the polycarbonate is easier scratched.