The Ocean Technology System (OTS) SP-100D2 Buddy Phone2 Surface Station transceiver is designed to operate with all single side band acoustic underwater devices within range and on the same frequency. The user simply places the OTS SP-100D-2 Buddy Phone2 in a secure area, lowers the 35 foot transducer cable into the water, turns the power on and talks via a hand held microphone. When any other divers within range and on the same frequency talk, their voice will be heard from the front panel speaker of the SP-100D-2. The OTS SP-100D-2 Buddy Phone2 is compact and operates on 8AA Alkaline batteries, ensuring hours of fun. For those who require extreme long life, two battery packs (16 AA) batteries can be utilized. You can monitor and talk to divers while action is happening. The OTS SP-100D-2 Buddy Phone2 is a must for all dive boats and/or dive operations.