the tread hole is M12*1<br>Feature 4 Jaw Chunk Diameter: 50mm <br>Connecting Thread: M12*1mm <br>Inner Diameter: 12mm-65mm, Outer Diameter:1.8mm-56mm Net <br>Weight:176 g <br>This four jaw chuck can fix solid round stick,hollow round stick,triangle,hexagon,square and other workpiece with strange angles. <br>Product material: aluminum alloy