The Transcend P8 Battery is only slightly larger than a deck of cards and can power Transcend CPAP devices for up to 14 hours at a time. It is compatible with all Transcend devices and the optional solar battery charger. The rechargeable option with solar power allows the patient to continue treatment while in remote areas without power or during power outages. Patients can regain their freedom while still receiving therapy. This charger should not be used to power the Transcend heated humidifier. It is rechargeable with AC, DC or solar power. The battery will charge even while connected to the machine.