This is the Sherwood Transmitter for the Amphos Air Wrist Scuba Computer Features: Part Number: STO800 Compatible with Sherwood Scuba&';s Amphos Air air-integrated dive computer. Before your dive, simply pair the transmitter with your dive computer and you&&';;re good to go. The transmitter&&';;s handy green led light lets you know that it&&';;s on. This wireless transmitter screws in to the high-pressure (HP) port of a first stage regulator and can communicate with the dive computer to allow them to display the cylinder gas pressure.