Phottix is a rapidly developing company that specializes in manufacturing photographic accessories. From its first days Phottix has been increasing its share in the international market, becoming highly acclaimed in the photographers’ communities worldwide.

Phottix Premium Series BG-D700 Vertical Grip/Battery Holder for Nikon D300 and D700 digital cameras, with same functions as Nikon MB-D10 Grip, with AF/On button, vertical shutter button, vertical common dial.  The Phottix BG-D700 Multi-Power Battery Grip allows the Nikon D300/D700 to be powered by two EN-EL3e batteries simultaneously - one in the camera body and one in the BG-D700 - effectively doubling your shooting capacity. The BG-D700  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.
Also has Tripod Socket

The grip is not compatible with original Nikon BL-3
The free BL-3 only for Phottix BG-D700 grip only.
Important notice: Phottix Kosmo does NOT work with this grip.

comes with:

Battery Holder for One EN-EL3e battery or one EN-EL4/EN-EL4a battery combined with the optional BL-3 Battery Chamber Cover (You can not use Original Nikon Made BL-3 on this grip)
Battery Holder for 8x AA batteries. 
A free Phottix made BL-3 Battery Chamber for EN-E4/EN-EL4a battery
Multilanguage User's guide