Super Quality External 2000mah Battery Pack Power Station for Apple Iphone 4 4s with Protective Back Cover Go Portable Case Charger for At&t and Verizon (Black) Ergonomic,form-fitting,fully protective ultra-resistant case-and-battery-in-one for your iPhone It allows you to charge and sync your phone while refilling your battery at the same time Intergrate power switch allows you to switch on/off the battery case,Only use the battery when you need it State-of-the-art battery technology extends the life of your iPhone for hours Rechargeable for over 500 cycles,Built-in short circuit and over-charge protection.Safety first