This is the ultra-slim protective iPhone case with a clip-on battery that provides supplemental power whenever it's needed. Adding only 2 mm to the thickness of the iPhone while allowing access to all its functions, the hard-coat case has a pleasing soft touch finish that also prevents the iPhone from falling out of your pocket. When extra power is desired, the trim lithium-ion polymer battery clips easily onto the case and immediately begins recharging the iPhone's battery without requiring any cords. Though only 7mm thick and weighing just 1.4 oz., it provides 1250 mAh of charging power. An included adapter lets the battery double as a universal charger for most any USB-powered device. The battery is recharged via USB using the included cable; LEDs indicate power level. For iPhone 4/4S. 5" L x 2 1/2" W x 1/2" D. (2 1/2 oz.)