Bao Xin 2200mAh Extended Power Pack for iPhone 4 4s External Battery Charge Case (Black) Advance 2200mAh Lithium Polymer Back up battery for iPhone 4/4S Standby Time: Up to 210hrs Audio Playback : Up to 28hrs Talk Time: Up to 8hrs.Weight: 71g Size:12.6*6.1*1.6 cm; Weight:63g;Material quality :general-purpose plastics ;Build in battery:Grade A lithium battery