Mpower External Rechargeable battery Booster for Apple iPhone 4 4S 3G 3GS iTouch iPod Black Universal usage, iPhone/iPod/iTouch, and rapid recharging Slim, convenient for carring, Cute design, keep in line with iPhone4 style(same thickness and width) Charge and sync your iPhone to iTunes without removing it from this booster One button for capacity remain indication Low self-consumption, less than 50uA