This is the ScubaPro Smart+ Transmitter For Scuba Diving Computers Features: Scubapro Galileo Luna/Sol - Smart Tec/Z Transmitter Convenience of Air Integration w/o Hassle of Dangling Hose Low-Profile Smart Transmitter Works w/Scubapro's Most Advanced Dive Computers Compatibility: Galileo Sol, Galileo Luna, M2 Screws into 7/16 Threaded High Pressure Port on First Stage Relays Tank Pressure and True Remaining Bottom Time (RBT) to Computer Easy to Use, Only Need to Pair it to Computer Once Coded Transmission Technology Prevents Interference of Different Computers Power: CR2450 Lithium User-Replaceable Battery Battery Rated for Three Years/150 to 200 Dives This low-profile Smart transmitter works with Scubapro's most advanced dive computers. It screws into a 7/16" threaded high pressure port on your first stage and relays tank pressure and true remaining bottom time (RBT) to the computer screen. Easy to use, you only need to pair it to your computer once -- the first time you use it. Coded transmission technology prevents interference between different dive computers. Powered by a user-replaceable CR2450 lithium battery that's good for three years or 150 to 200 dives. Compatible with Galileo Sol, Galileo Luna and M2 personal dive computers. "