Navigator Adult Scuba Mask has oversize lens which enhance diver’s peripheral viewing. The Navigator has 4mm tempered glass lens, high-impact composite frames with double-edge skirts which prevent leaking, quality soft-flex T.P.R.* and silicone (some models) materials for enhanced comfort and easy fitting, easy adjustable swivel buckle system, and low interior volume designs for easy clearing. Thermal Plastic Rubber (T.P.R.) is also used which produces the look and feel of silicone. This mask is recommended for adults only.