Oceanic OCi Wireless Dive Watch Computer - Watch Only For Scuba Diving Powered by Oceanic's Exclusive Dual Algorithm- Your choice between Pelagic DSAT (Spencer/Powell data basis) or Pelagic Z+ (Buhlmann ZHL-16C data basis) Wireless Air Integrated Technology *Wireless Transmitter not included Advanced Digital Compass with North, Reference, Auto Home, and Declination Adjustment (see NOAA's NGDC geomagnetic chart) Free and Tech Free dive modes Multiple Transmitter Capability & switch between 4 independent transmitters, with up to 4 nitrox mixes to 21-100% O2