Bao Core BXT External Battery for iPhone 4 / 4S iPhone Case Extended Power Bank Pack (2200mAh,Blue) High Quality and Finest Advance 2200mAh Lithium Polymer Back up battery for iPhone 4/4S Extend standby time up to 210 hrs for iPhone 4/4s;talk time up to 8hrs;Audio playback 28hrs Size:13*6.5*2 cm; Weight:75g;Material quality :general-purpose plastics ;Build in battery:Grade A lithium battery Best iPhone 4 4S case .This backup battery pack charge your iPhone 4 whenever you want ,also it's a protective case which protect your iPhone all around Soft touch ,avoid you iPhone 4/4S from slip.Package included :BXT power bank X1,user manual X1