iPhone Power Pack case+external battery for 3G, 3GS Black Green

Product Features:
Compatibility: iPhone 1st Generation, iPhone 3G (8GB, 16GB), iPhone 3GS (16GB, 32 GB)
Extended Battery: Doubles battery life of iPhone 3G 3GS-provides up to 8 additional hours of talk time and 30 additional hours of music playback time
Color: White Green
Charge & Sync: Charge and sync iPhone 3G 3GS with iTunes without removing it from the Power Pack
Technology: Smart battery technology drains battery of the Power Pack first before switching to the iPhone's battery
Rechargeable: Convenient rechargeable battery allowing you to always have a battery charging backup when you are away from a AC outl
Warranty: 1-year Manufacturer