Neewer Universal Quick Release Plate Clamp (QR-50) All-metal materials, CNC precision machining, surface oxidation treatment Built-in spirit level and precision ruler With the female thread of UNC 3/8" standard, the width of the dovetail groove in the bottom is about 20mm Compatible With: All Arca-Swiss standard quick release plates, including Benro / Arca Swiss / Acratech / Kirk / Wimberley / Gitzo / Manfrotto and etc.