Standard 15mm rod clamp, fits all 15mm rods,15mm rod rail system. There are 1/4" and 3/8" thread holes placements which are versatile.Mount a monitor/teleprompter on your camera rig when it is on a tripod/slider. There are thumb screw and wingnut on both of the holes, you can tighten this on both rails. With standard 60mm spacing, fits standard 15mm rod system. Made of black anodized aluminum,Super Lightweight 15mm rail block.