T-Mobile Portable Back Up Battery Charger with USB Cable Charge Any Dead Cell Phone Battery With This Universal Battery Booster (Devices with USB Cable Only) Portable back-up battery charger with USB cable Compact size for convenient storage and travel Includes USB-A-to-USB-Mini B cable Built-in battery tester with level LED indicator Portable back-up battery charger with USB cable Built-in battery tester with level LED indicator Compact size for convenient storage and travel High-capacity Li-Ion battery doubles handset use Includes USB-A-to-USB-Mini B cable