Neewer 140mm Professional Rail Nodal Slide Metal Quick Release Clamp for Camera with Arca Swiss Compatible Multi-purpose rail nodal slide with Arca standard screw-knob clamp, precision laser engraved scale and spirit level, excellent for panoramic and close-up photography Clamp with Captive Knob Stops at Maximum Opening CNC precision machined from light weight aircraft grade aluminum All metal construction Black Hard Anodized Finish with smooth surface