Portable Iphone 4/4s chargers ?

its a basic cover which comes with a usb cable you charge the cover via usb using computer/laptop and then put the cover on the iphone the cover has a on and off button so whenever you need to charge your phone just press on and it will start charging otherwise leave it off and it will protect your phones backcover compatible with the iphone 4 or even 4s 20 is the final offer for more information plz contact me on 07516884716