This Battery Kit features the ResMed Power Stations (RPS) II and comes with all the parts needed to run a ResMed S9 Series machine. The ResMed Power Station II is a long-life, lithium-ion battery. It is suitable for home or travel. It can be used with all S9 Series CPAP or VPAP units including the use of the humidifier. Use the standard S9 power supply and cord to charge the battery.