iWalk [Link2500i] 2500 mAh Rechargable Backup Docking Battery for iPhone 4s/4, 3Gs/3G, and more [Apple Certified]

iWALK Link 2500i Apple Lightning Compact Rechargeable Docking Backup Battery works with all mobile devices with 30 pin Lightning connectors. Whether you're working a trade show or on the ski slope, power will never be in short supply with the Link 2500i. Unique, compact design to match the look of your phone. Charges the Link 2500i and your phone simultaneously The Lithium-ion power cells provide high capacity in a compact size LED Battery power Indicator lets you know the power level.