The Philips Respironics 12 Volt DC Power Cable System allows you to power your DreamStation machine from an external 12-volt power source such as a cigarette lighter socket or a deep cycle marine battery. The DreamStation can connect directly to a battery using the included alligator style cord and attaching the DC cord to that. Because the 2 cords can separated, this system gives you the option of plugging the DreamStation into a cigarette lighter power socket, or connecting to a stand alone battery.