This excellent quality rail is for use with all digital and film SLR cameras and is compatible with most Nikon, Minolta and Pentax macro and EOS bellows, macro shot extension tubes, or macro lenses such as the Canon FD and FL .Smooth rack and pinion movement provides extremely fine focusing adjustments. The rail has a geared drive system which greatly enhances accuracy and speed of adjustment of the rail. Two 6" rails allow movement in four directions, right, left, forward and backward. Mounts on, and accepts 1/4x20 threaded screws, will fit most tripods and copy stands. Positive locking knobs assure rock-steady focus Focusing rails are essential accessories for macro photography, which requires precise distance modifications and a steady hand, as well as other situations where accurate camera positioning is crucial.