Seidio BACY38SSG2T-BK Innocell 3800mAh Super Extended Life Battery  for  T-Mobile Samsung Galaxy S 2-Battery - Retail Packaging - Black Comes with a black replacement door to accommodate the larger size of the battery Keeps your phone charged and ready to go, even with heavy phone and data usage Capacity: 3800mAh To obtain the full capacity of your battery, leave the battery/your phone on the charger for an additional 2-3 hours after the charging indicator turns green or the battery status shows full. For use with: T-mobile Samsung Galaxy S II