This power adapter can convert 12V or 24V DC (Range 10V ~ 30V) power to 24V DC power with special configuration power cable with a special connector compatible with ResMed AirSense 11 CPAP Machines DC Converter Features: This DC to DC power adapter can convert variable 12V DC (range 9V -32V) to 24V regulated stable DC power. Maximum output 65W This DC to DC power adapter's input side has 5.5 x 2.5mm Female barrel connector with two 16AWG bare wires. The output is a 5.5 x 2.5mm male barrel connector with 18AWG wires. It is very easy and flexible to connect with batteries and other power source. Wide input range: 9V ~ 32V Output: Max. 65W Small size: 90 x 36 x 27mm ( or 3.5" x 1.5" x 1.1") Light weight: 142 ( or 5 oz) If your battery power output cable has a 5.5 x 2.5mm barrel connector with center positive polarity, you can directly plug it the power converter input side, then connect power converter output end to CPAP machine power jack: Battery & CPAP Machine are Not Included. Cigarette Plug Input Cable: You may also use Car cigarette input cable to link the power converter to a DC power source with output voltage range 9v ~ 32V. The input cable one end has a 5.5 x 2.5mm male barrel connector that can plug to power converter input port, another end is a cigarette plug that can plug to a car/truck cigarette lighter socket. Battery & CPAP Machine are not included. Package contents: 24V DC Power Converter for ResMed Airsense 11 x1 Cigarette Plug Input cable x 1