1900 mAh Rechargable External Backup Battery Emergency Battery Charger for iPhone 4, 4G, 3GS, iPhone 3G, 2G, iTouch, iPod Nano Compatible with ALL iPod nano, iPod touch, iPhone 2G 3G 3GS 4G 4 Can charge your iphone and battery pack at the same time using AC/USB power cable Charges your iPhone from 10% to 100% in just 2.5 hours. Remove the battery and your iPhone is charged 100% 1900 mAh battery, strongest clip on battery in the world with no cables for the iPhone. Excellent quality with high-end parts. Small enough to keep connected to your iPhone or iPod