The Pilot-12 PLUS is an uninterruptible power supply (backup battery) to ensure that your prescribed PAP therapy continues seamlessly even during a power outage. Can also be used as a portable, standalone power source. Take it travelling and use it to power your PAP device when the mains power isn't available. Provides 1-2 nights of continuous run-time on an average pressure setting with the humidifier and heated tubing disabled. The optional Co-Pilot 12 expansion unit can be used to further extend this run time to 3-4 nights.