Power your ResMed Machinewhile you're away from an outlet or stuck in a power outage. Great for travelers! Please note this item is not eligible for further discounts. *Please note - If purchasing 2 or more batteries, your order must be purchased using PayPal. You will also be contacted by our customer service team to verify your order. The ResMed Power Station (RPS) II is an external lithium-ion battery that allows the operation of compatible ResMed devices where main power is not available and provides backup power in case of an unexpected mains power failure. Long-lasting powerdoubledRPS II provides extended hours of run time with a single battery. The power capacity and operation time can be doubled by using two batteries, with an automatic transition from the primary battery to the reserve. Convenient and portableRPS II provides battery power for the device in case of power outages or where mains power is not available. RPS II is suitable for both home care and hospital care. It is ideal for travel or when additional mobility and freedom are required, such as on the back of a wheelchair. Meets IATA Transportation RegulationsSafety alerts and indicator audible and visual alerts beeping sound and orange light (LED) indicate that the battery needs to be recharged. The battery-charge display indicates the charge level. Technical specifications battery type: Lithium-recharge time: Less than 4 hours from fully empty to fully chargedDimensions (L x W x H): 9.06 x 4.96 x 1.02 inches battery Weight: 2 pounds.