The ResMed AirMini 65W DC Power Converter allows you to operate the travel friendly ResMed AirMini CPAP Machine from a 12V or 24V DC Power Source like those found in many cars, boats, trucks and other vehicles. The total length from end to end is 9.8 feet Using the DC converter via a vehicle cigarette lighter socket: Position the converter into the AirMini CPAP machine power inlet/DC input socket.Plug the converter into the vehicle cigarette lighter socket.The light on the converter will glow green when it powers on. If the battery is low, the light will glow to an amber color. If the battery you are using is too low to power the AirMini, the converter and light will turn off. (some vehicles require the ignition key to be turned to the accessories position to provide power to the vehicle cigarette lighter socket). ResMed recommends connecting a deep cycle battery to the converter to power your AirMini, as deep cycle batteries are optimized for frequent heavy discharges.