Cetatek aquabionic M11 Twin Lens SCUBA Diving Mask Colored framed SCUBA diving mask with twin 4mm tempered glass lenses Very soft surgical grade silicone skirt; twin seal design provides comfort and watertight performance Black frame masks have black silicone skirt; colored frame masks have clear silicone skirt Push button buckles with silicone spring for easy single hand strap adjustment Low volume 170 cc; weighs 7.4 oz.; available in two sizes