1. The dial indicator with center display is a measuring tool that transfers the relative position of the workpiece center to the dial via a lever and converts it into angular displacement of the pointer. It is a precise, practical, and visible tool for locating the relative center of machined workpieces, such as the circumference and inner bore of the workpiece. 2. 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. 3. Operation from horizontal to vertical machines and from inner to outer diameter is possible by simply replacing the inductor without modifications. While the machine spindle rotates, the display remains stationary in any desired position, allowing the operator to have both hands for precise table positioning. 4. With a measuring range of 0 to 0.15' and a resolution of 0.0005', this COAX coaxial centering indicator can quickly and accurately set the center for drilling and milling on horizontal or vertical machines. When the spindle rotates, the scale faces the operator, enabling easy centering.