SUNWAYFOTO 50mm Screw Knob Clamp Arca Comp DDC-50i 1/4" 3/8" Sunway SUNWAYFOTO brand Arca-Swiss compatible Accepts QR's from RRS Wimberley, Arca Swiss, Kirk, Markins, etc. All metal construction 3/8"mounting hole and 1/4" adapter Includes bubble level