The Canon BG-E11 Battery Grip replaces the current LP-E6 battery with an ergonomically friendly battery grip for the Canon EOS 5D Mark III with space for 2 batteries, thus doubling your camera's battery power. In case of 'emergency' situations where both of your batteries have depleted, you can temporarily power your camera with AA batteries.
Built in the same magnesium alloy, weather-proof, material as the 5D Mark III, it is also adorned with duplicate buttons to make vertical shooting a more enjoyable, and certainly easier, experience - consisting of controls for AF start, Focus Point, AE-lock as well as a second multi-controller, and a second control dial.