BioLogic Reecharge Case for iPhone Integrated 1400 mAh lithium polymer battery Charge out function allows the case to charge other USB devices Hard plastic case and silicone liner protect your iPhone against scratches and knocks RidgeSeal case design protects against weather, sweat, and grime -- rated IPX-4 Compatible with iPhone 4S, iPhone 4, iPhone 3GS, and iPhone 3G