The system comprises a breathing loop (mouthpiece, hoses, counter lungs and backpack) with associated electronics module, and two independent gas cylinders. One contains 100% compressed oxygen which is added to the breathing loop as the diver consumes it. The second cylinder typically contains compressed air “diluent” to compensate for compression in the breathing loop as the diver goes deeper. It’s also a backup system, containing enough oxygen for the diver to breathe directly in an emergency.
