... out of power,it can be just attached perfect Attachable Battery Pack for iPhone and iPodFeatures: 1,Made for iphone4,3G.3GS ... ,touch 2,Patent safety design: Multi-safety design for overcharging, temperature, short ... 4,Non-slip grip design Product Modle:T4 Color :white Battery:Lithium-polymer battery Capacity:1500MAH(3.7V) USB Output voltage:5V USB ...