This grip is designed specifically for the Canon 5D Mark II. It allows users to load one or two LP-E6 battery packs. With two packs, the already-impressive battery life is doubled, compared to using a single pack. This is especially useful when taking advantage of the camera's movie mode or Live View mode - operating modes that use more power. Furthermore, this grip provides full vertical shooting controls, which can be independently turned on or off as the photographer needs to enhance camera handling, especially for shooting vertical pictures.