The Aquacom STX-101 surface transceiver is a 5-watt, multichannel, single sideband underwater telephone designed with the Professional Search & Rescue Teams in mind.  The STX-101  offers four channels that match the SSB-2010.  This system is tough, powerful and a must for any serious Search & Rescue Team.  STX-101  is also very affordable!

Calm seas: Greater than 1,500 meters. Sea state 6: 200 meters.
Frequency Range:  30 to 35 kHz.
Audio Bandwidth:  300 Hz to 3,500 Hz.
Automatic Gain Control:  120 dB dynamic range (AGC)
Acoustic Output Power:  5 watts (nominal)
Microphone/Speaker:  Hand Held , dynamic, 200 ohm./Heavy duty front panel speaker with On/Off control.
Transducer:  Piezoelectric type on a 55' cable
External Power:  12 volt, DC @minimum of 4 amps.
Battery Type & Life:  (2) 6 volt lantern batt. (heavy duty with springs). 20 hours continuous use assuming 10% duty cycle.
Squelch:  User adjustable from the front panel.
Receiver Sensitivity:  Greater than 100 dBv.
Housing Dimensions:  D: 10.60", W: 14.00", H: 6.500", Weight: 12.5 lbs. w/batt.