The Mophie Juice Pack mobile external battery charger case is a must-have for your Samsung Galaxy SIII. It keeps the device powered while safeguarding it from dust and scratches. This case has a rechargeable battery that charges your phone. With its functional standby switch, it lets you charge the Galaxy S III at your convenience. This external battery charger case protects your device from overcharge, over-discharge and short circuits. You can charge the case by connecting it to any USB power source. Its 2-piece slider design is ergonomic. Made of a tough material, this case guards your phone without limiting access to any of the controls and ports.