Mounting shank: 3/8 inch. Capacity: 5/32 inch to 4-1/4 inch inside diameter or 0 to 4-1/4 inch outside diameter. Speed: Spindle rotates to 100 RPM. Exceeding this speed is not recommended. This is a professional indicator for finding the center of the workpiece on a drill or milling machine (alignment) and the center lateral diameter. The center test indicator is a new measuring tool that uses a lever to transmit the relative position of the workpiece center to the indicator and converts it into pointer angular displacement. It is an accurate, convenient and visible tool to find the relative center of the machined workpiece, such as the circumference and inner hole of the machined workpiece. Operation from horizontal to vertical machines and from inside to outside diameter is possible by simply replacing the inductor, without any changes. As the machine spindle rotates, the indicator remains stationary in any desired position, leaving the operator with both hands free to accurately position the worktable. Supporting measurement range: 0-0.15 inch, resolution: 0.0005 inches, this CO-AX coaxial centering indicator can quickly and accurately set the center for drilling and milling on horizontal or vertical machines. As the spindle rotates, the the operator, allowing /her to center. Coaxial Centering Indicator x 1, Restraining Rod x 1, Center Point Sensor x 1, 2 inch, 4 inch and 6 inch Straight Plugs x 1, 2 inch, 4 inch and 6 inch Curved Plugs x 1, Twisted Wire x 2, User Manual x 1, Storage Box x 1. An essential tool set to meet your needs!, Weight: 2.17816714856 Pounds, Manufacturer: Prterver