This DC cord is compatible to Philips Respironics DreamStation series (CPAP Pro, Auto CPAP, BiPAPs). One end connects to vehicle's cigaratte lighter outlet with 12v DC, the other end connects to your CPAP directly. With this DC power cord, you won't need a regular AC charger.
Battery cable: if you won't have access to cigaratte lighter outlet, you can purchase the batter cable option which allows you connecting to battery directly.
Humidifier: this 12v DC shielded DC charger is compatible to CPAP with a humidifier. However, using humidifier will quickly drain your batteries. So unless your vehicle/camper/boat has a big battery capacity, we do not recommend you use humidifier with your CPAP machine while camping or travelling.