This is the Apeks Wireless Transmitter Features: Hoseless gas pressure transmission for the Apeks DSX, Aqualung i450T and i750T and any of Shearwater computer Once set, the transmitter is permanently paired and will not accidentally pair with other computers Battery is user changeable and commercially available Nitrox compatible up to 100% Apek&';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.