The DeVilbiss IntelliPAP has a 12 VDC plug with Positive Polarity, or sometimes called Positive Hot. That is the tip of the cigarette lighter connector is in contact with the positive polarity of the car or battery, and is transmitted to the inside of the barrel connector at the machine.
* Cord Length: 6 Ft* Barrel Connector is a 2.1 mm ID x 2.5 mm OD (fits most Respironics machines with a 12 VDC connection*, as well as some other brands.)
