The ATM-885 is rated to 2000m and includes 21V Alkaline batteries, 18 amp HR, modem electronics, and an integral transducer - directional or Omni-Directional.
The ATM-887 is rated to 6000m and includes 21V Alkaline batteries, 28 amp HR, modem electronics, and an integral transducer - directional or Omni-Directional.