PowerSkin PoP"n for iPhone 4/4S - an attachable external battery charger that sticks onto your existing iPhone 4/4S. PowerSkin PoP"n battery chargers provide a strong boost of power in a revolutionary design. Quickly and securely attach the PoP"n battery charger to your smartphone, even over existing cases. This slim, light-weight charger fits discretely in any bag, and it"s fun to hear the POP as you take it off once your phone is recharged. Connectors available for most devices, making it the ultimate universal power pack, so STICK IT and GO to keep life PoP"n, because battery life is life