The offGRID Backup Battery Case for iPhone 4 & 4S is the thinnest, lightest and most efficient iPhone backup battery case available. This case has an ultra thin rechargeable battery built inside of a snug fitting, low-profile protective case that promises to double the battery life of the iPhone 4 & 4S. The power /status button allows the user to determine the charge level and status quickly ,with just one soft touch button and a series of blue lights.