Efo is at it again with another iPhone 4 accessory, this time it serves dual purposes actually to charge the iPhone 4 and it has a USB port to charge anything else that might need the extra juice.
The sleek power pack snaps inconspicuously onto the back of your iPhone, adding only a few millimeters of thickness, but more than doubling the battery runtime. If prioritizes consumption, pulling power from the Power Pack first, maximizing the iPhone’s internal battery.
Video Demonstration : http://www.youtube.com/watch?v=hGkBeObhaGE
Price : US$30
Battery type : Lithium-ion battery
Weight : 74g
Product compatibility : iPhone 4/4G
Standby time : upto 390 hours
Talk time : upto 6.5 hours
Internet use : upto 6.5 hours on 4G and upto 8 hours on Wi-Fi
Audio play : upto 31 hours
Video play : upto 9 hours