iPhone 4 battery cases -

The powerpack back-up charging case designed for the iPhone4. Each case incorporates a powerful back-up battery built in to its shell, this added battery power significantly increases the available usage time of the phone. Each case comes with a USB for charging. To charge your phone, insert it into the case and hold the power button for a few seconds, as simple as that The cases are the thinnest profile available today and add about 3mm to the depth of the phone and are extremely light weight.