The M101A G.divers is a receive-only unit with a single channel. Any standard mask strap or full face mask can be used with the M101A. It can be held and shared by multiple divers due to the high quality speaker. The M101A uses a 9V alkaline battery when the battery is low and has a "low battery" alert that beeps every 30 seconds.
It's the ideal instrument for Instructors and team leaders to communicate with divers who don't wear IDMs because it has the option of integrating a transceiver unit.