This battery grip/holder is compatible with Canon EOS 550D SLR cameras. It has all the same functions as the original Canon BG-E8 battery grip. The grip has a built in vertical shutter release button, and can hold two LP-E8 lithium-ion battery packs, or six AA batteries using the included battery holder. Additionally, it supports features such as AE lock and FE lock, and retains access to the Index/Reduce button, main dial, AF-Point Select button, and Aperture/Exposure Compensation Buttons. Features: Pro Battery Grip for Canon EOS 550D SLR Camera Hold 6 AA batteries or 2 LP-E8 Li-ion batteries. Vertical shutter with half-press function. More comfortable vertical shooting. Doubling the battery capacity of your camera, effectively extending your shooting time. Professional edition with vertical-grip shutter-release button, main dial, AE-L button, Index/Reduce button and Exposure button. Tripod screw mount. Same functions as the original battery grip Canon BG-E8. High quality product with a big discount from the original one.