MB-D10 Battery Grip for Nikon D700/D300

The Nikon MB-D10 Multi-Power Battery Pack
allows the Nikon D300 or D700 to powered by two EN-EL3e batteries simultaneously - one in the camera body and one in the MB-D10 - effectively doubling your shooting capacity. The MB-D10 also provides a comfortable vertical grip with an additional shutter release and scroll wheel for easy access to the camera functions when shooting in the vertical orientation.
With the included MS-D10 AA battery holder, users can power the camera with 8 AA batteries or use a Nikon EN-EL4 or EN-EL4A battery (sold separately) with optional BL-3 Battery Chamber Cover to obtain higher frame advance rates (8 Frames per second in the D300) than the EN-EL3e battery can provide.