1. Mounting Shank: 3/8'. Capacity: 5/32' to 41/4' inner diameter or 0 to 41/4' outer diameter. Speed: Spindle rotates at 100 RPM. Exceeding this speed is not recommended. This is a professional indicator for locating the workpiece center on a drilling or milling machine (alignment) and the side center diameter. 2. With a measuring range of 0 to 0.15' and a resolution of 0.0005', this COAX coaxial centering indicator can quickly and precisely set the center for drilling and milling on horizontal or vertical machines. When the spindle rotates, the scale faces the operator, allowing them to center it. 3. Operation from horizontal to vertical machines and from inner to outer diameter is possible by simply replacing the inductor without any modifications. While the machine spindle rotates, the display surface remains stationary in any desired position, allowing the operator to have both hands for precise table positioning. 4. The centerindicating dial gauge is a measuring tool that uses a lever to transfer the relative position of the workpiece center to the dial gauge and converts it into an angular displacement of the pointer. It is an accurate, practical, and visible tool for finding the relative center of the machined workpiece, such as the circumference and inner hole of the workpiece.