The Canon BG-E7 battery grip is the official Canon battery-grip for the Canon EOS 7D digital SLR. It gives the photographer alternative power options as well as vertical control.
The BG-E7 will hold up to 2 Canon LP-E6 batteries to give a increased shooting duration. As an alternative, the BG-E7 grip can also be used with 6 AA batteries. This not only increases shooting times but also means that the AA batteries can be used if your lithium ion batteries unfortunately fail. The Canon BG-E7 grip also makes holding your 7D in the vertical or portrait position more easier and comfortable. Shutter release, main dial, AF Point Selection, AF/FE Lock, Index, Aperture, Exposure Compensation Button and Reduce Button functions are all on the grip, making usage of the camera more convenient when shooting in portrait format.