Greatly improve your stability and accuracy;
Great for digital, film and video cameras;
It adds security to hand-holding a camera, and was designed to be used only with cameras that havea built-in power booster or grip, or where an optional power booster or extension grip has been added.
It attaches with one end to the eyelet at the top of the camera, and the other end to the eyelet in the base of the booster/grip.

Important Note: Only fits on cameras with built-in booster grip or with an added extension grip

FOR:
Canon EOS-1V/1/1N/1D/1D Mark II/1D Mark IIN/1D Mark III/1Ds/1Ds Mark II/1Ds MarkI II/III
Canon EOS-3 w/Power Booster E1
Canon A2/A2E w/VG-10
Canon Digital SLR D200D, EOS-10D/D60/D30with BG-ED3
Canon Digital Rebel with BG-E1 Grip
Canon 300D with BG-E1 Grip
Canon 20D/30D with BG-E2 Grip
Canon 40D with GB-E2N Grip
Canon Digital Rebel XT/XTi with BG-E3 Grip
Canon 350D/400D with BG-E3 Grip
Canon 450D with BG-E5 Grip
Canon 5D with BG-E4 Grip