Easy breathing & air circulation - air circulation within this dive mask is achieved with an orinasal pocket so that co2 build-up is not mixed with fresh air; one-way circulation keeps the mask clear. Clear field of vision - designed wider and sits closer to the face than other visors, giving a broader field of vision and less volume buoyancy while diving. Durability and scratch resistance - full-face scuba mask has a transparent polycarbonate visor, both sides of which are coated in siloxane resin for improved scratch and chemical resistance. Head harness & fast rotating buckle ii - the six straps of the head harness hold the mask in a firm position due to their low elasticity; fast rotating buckle system for comfortable and quick doffing and donning on the surface. Gsm g.Divers - wireless underwater transceiver unit, with the autonomy of approx. 30 hours in receiving mode, and range