O2COOL 4004 Emergency Power Charger Battery-operated emergency power charger with carrying strap Recharges most cell phones, MP3 players, and other 12-volt devices No AC power required; runs off of 8 D-cell batteries (not included) 12-volt cigarette socket and USB socket; manufacturer-approved adapters required Measures 3-4/5 by 9 by 4-1/2 inches