QCell Samsung Galaxy S2 AT&T SGH-i777 Slim Battery (NOT Compatible with i9100/T989/D710) AT&T Galaxy S2 Slim Battery by QCell! Premium Quality and Best Material used! Designed in Canada! Slim Profile Design with Maximum Cell Efficiency! Able to use original batter cover! DYNAStop overcharge IC stopper built in! Voltage: 3.7V / Li Ion Battery