Satechi iCel 5200 mAh (2 amp) Battery Extender Pack and Charger for iPhone 4, 3G & 3Gs, iPod Touch 4G, BlackBerry, HTC EVO, HD7, DROID, Samsung Galaxy S, EPIC, Flip & Vado HD Camcorders Instant power - recharge your iPod, iPhone 4, 3G & 3Gs and other mobile devices battery. 5200 mAh (2 amp) 18 Watt Compounded Interconnection Battery (More stable and longer life compared to lithium batteries). Battery life indicator & auto OFF feature that detects when fully charged. While charging the iPhone, the battery pack can also be recharged simultaneously. Also able to charge cell phones, PDAs, USB camcorders and mp3 players like Zune, Sansa, and Creative Zen.