No more sore mouth at the end of the dive. Breathe through your nose and enjoy an unparalleled field of vision. This integrated Diving Mask has a balanced, on demand, regulator, certified for cold water use and a six strap harness. Wireless underwater transceiver unit, with the autonomy of approx. 30 hours in receiving mode, and range of operation of 200-250 meters (calm sea water), Light weight, powerful single channel and “push to talk” communication system make the GSM Gdivers the perfect addition to any training class or guided tour. The unit operates on the same frequency as all other OCEAN REEF units and most popular wireless communication units on the market.The GSM Gdivers uses a 9V alkaline battery and has a “low battery” alarm which beeps every 30 seconds when the battery is low.