Andoer NNR-200 200mm Professional Rail Nodal Slide Metal Quick Release Clamp for DSLR Cameras Camcorder DV Multi-purpose rail nodal slide with AS standard screw-knob clamp, precise laser engraved scale and spirit level, excellent for panoramic and macro photography. Clamp with captive knob stops at maximum opening. CNC precision machined from lightweight aircraft grade aluminum alloy. All metal construction. Black hard anodized finish with smooth surface.