System-S Backup Battery Charger Extender For Apple iPhone / iPod Touch / Classic / Video / Nano / Mini / Photo Uses four AA-size batteries, which can fully charge your inside battery Pocket sized, lightweight, durable, small and handy Eliminates traveling with a ac adapter or charging cradle Charges your battery or provide backup power Works also with: 4 rechargeable 1,2 and 1,5V mignon AA batterys