Aqua Lung's Transmitters, used in conjunction with a compatible wrist computer, allow you to monitor current pressure and gas time remaining without a stiff high pressure hose, while providing a more streamlined profile. Hose-less Gas Pressure Transmission for the i450T, i750T and i770R. Once set, the transmitter is permanently paired and will not accidentally pair with other computers. Battery is user changeable and commercially available. 2 transmitter versions available: Nitrox compatible up to 40% or 100%.