HiCool&trade; Scuba Snorkeling Diving Mask with HD Tempered Lenses HD Clear Tempered Lenses, withstanding pressure from water and scratch from sand without undermining the clarity Food-Grade liquid silicone injected skirt and strap, durable and comfortable to wear Easy adjust buckles attaching on skirt directly, which makes swivel function more flexible and may fits a wide range of face shapes Patented Soft and shaped dimples on both sides of nose purge valve making equalization easily to sooth the pressure to your ears Low in profile and internal volume, increasing the leakproof and waterproof