This 4-jaw self-centering chuck with dovetailed jaws is great for small bowl and plate turning and features jaws that grip by clamping around the work piece or expanding to fit a turned recess. the minimum diameter required for clamping around the work piece is 1-1/4-Inch and the minimum diameter required for expansion is 1-13/16-Inch. includes t-handled wrenches wood screw point and machined chuck lever. compact design is ideal for smaller lathes. specifications: • type: 3-3/4-Inch 4-jaw self centering • size: 1-Inch • tpi: 8.