The BG-E21 Battery Grip for Canon EOS 6D Mark II from Canon is a battery grip designed for use specifically with the Canon EOS 6D Mark II digital SLR camera and accepts one or two Canon LP-E6 batteries. With two batteries installed, your shooting time is effectively doubled. Moreover, when one battery is drained, it can be removed and recharged while you continue shooting with the other battery. In addition, the BG-E13 can utilize 6 AA batteries and comes with a battery tray designed to hold 6 AA/LR6 batteries. It can also be powered by the optional ACK-E6 AC Adapter Kit.