Designed for use with the new canon eos 5d mark iii digital slr camera the bg e11 battery grip doubles the battery life with two additional lp e6 batteries with the added flexibility of using aa batteries as an emergency back up as a vertical grip the bg e11 has duplicates of the af start ae lock and focus point controls plus an additional command dial and multi controller holds two lp e6 batteries use aa batteries as an emergency back up built in control buttons for vertic