The Battery Backup Pack adds a portable power supply to your device via the USB port. Equipped with four conventional 1.5-volt AA batteries, your PDA will run for a few hours longer. The duration depends on the batteries used and the power consumption of the PDA (+/- 8 hours). With this charging adapter you can use and charge your PDA at the same time. This works with Allen devices that have a USB cable and can also be charged via the USB interface (almost every PDA includes this function). Can also be used with 1.2V Mignon AA batteries, unless the actual battery is completely empty. Compatibility: for all PDAs that can be charged via USB and that already have a USB cable. Scope of delivery: 1 battery charger for PDAs (no batteries, no PDA, no USB cable)