The DC Converter 24V 90W For S9™ Machines enables S9 Series CPAP Machines to be powered using a 12V or 24V power source such as those found in a car, boat, RV, or other battery. This converter also allows for use of the H5i humidifier and ClimateLine heated tubing with the S9 CPAP machines while on 12V or 24V DC power.