Backup Battery for iphone 3G, iPod, Nano Specification: 1.Capacity: 1900mAh 2.Input: 5V/700mA 3.Output: 5V/500mA 4.Dimension: 113*66*21 (mm) 5.Weight: 70g (including a 75cm length USB cable) Features: With this kind of backup battery for iphone 3g,you don't need to worry about running out of your iphone batter.it's good for traveling,light and portable to take away,a great Companion, wherever you go.