Xpal iPower for iPhone 3G/3GS Protective Case with Rechargeable Battery - AP1200 - AP1200 - Buy.com
Protective iPhone case with built-in battery
Patented Powersafe technology
Smart LED power indicator
Non-slip grips
Rechargeable up to 500 times
Uses Mini USB to recharge internal lithium polymer battery
Replaces 2000 AA batteries
Standby time: Up to 255 extra hours
Music time: Up to 20 extra hours
Talk time: Up to 4 extra hours
Internet time: 4 extra hours
Video time: 6 extra hours
In the box:
Xpal AP1200 iPhone Protective Case with Rechargeable Battery
USB Cable
Users Manual
Xpal iPower for iPhone 3G/3GS Protective Case w/Rechargeable Battery-AP1200 $49.99 FS 
