... out of power,it can be just attached perfect Attachable Battery Pack for iPhone and iPodFeatures: 1,Made for iphone4,3G ... ,Non-slip grip design Product Modle:T4 Color :white Battery:Lithium-polymer battery Capacity:1500MAH(3.7V) USB Output voltage:5V USB ... the side, used for data transmission or charging 1500mA Attachable Battery Pack plus Sync Cable Made for iphone, iPod touch