The ResMed DC converter 24 V 90W for the air 10 series machines powers the ResMed air sense and air curve units. Use the DC converter when away from home or when there is a power Outage. This DC power converter powers both the unit and the humidifier so there is no need to turn off your humidification. Take your ResMed unit with you on a boat, in the car, or any place with DC power capability. Please see the link to the user guide below for important notes and instructions.