Now provide new updated version,with two screw mount on the bottom and laser etched ruler. Introduction Two slider allow movement in four directions, right, left, forward and backward. the macro slider has smooth rack and pinion movement to provide extremely fine focusing adjustment. back. Positive locking knobs assure rock-steady focus.It can be divided into two one-way macro slider, it is very simple to mix and split. Suitable for: All DSLR or DC with standard 1/4" screw hole. Specification: Material: Metal Weight: 500g Color: Black Length: 160mm Width: 93mm Height: 24mm Move Range: 100mm Package Included: 4 way Focusing Rail Slider x1