The Canon BG-E4 Vertical Grip/Battery Holder is an accessory for their EOS 5D camera which improves the handling of the camera. The BG-E4 also adds a vertical shutter button, main control dial, AE/FE lock button, AF point selector, and doubles your potential shooting time.
The BG-E4, made with the same magnesium alloy construction as the 5D camera itself, holds up to 2 BP-511/511A/512/514 batteries. Alternatively, it can use 6 "AA" batteries (only in temperatures above 50°F/10°C).
The vertical shutter release and main control dial help make shooting with the camera in a vertical position just as comfortable as shooting horizontally, and the BG-E4 adds a third strap eyelet to the camera so that you can use the optional E1 Hand Strap.
BG-E4 Vertical Grip/Battery Holder