The Canon Battery Grip BG-E7 is an optional battery
grip designed specifically for the Canon EOS 7D. It allows users to
load a choice of one or two LP-E6 battery packs (not included). With two
packs, the already impressive battery life is doubled, compared to
using a single LP-E6 pack in-camera. This is especially useful when
taking advantage of the camera's movie mode or Live View mode -
operating modes that use more power. In addition, with the included
battery magazine you can alternatively also power the camera off six AA
batteries.
Furthermore the BG-E7 provides full vertical shooting
controls, which can be independently turned on or off as the
photographer needs to enhance camera handling, especially for shooting
vertical pictures.
Note! Does NOT include any batteries