1. Precision Measuring Tool: This coaxial centering indicator is a secondary measuring instrument for machine tool alignment. With a measuring range of 0 3mm, it is for determining the relative position of the inner and outer centers to the spindle center of the machine tool. 2. Versatile Probe Kit: Includes three types of centering indicator probes straight, curved, and point probes. This versatility allows for various applications including inner circle, outer circle, and small hole centering, adapting to different measuring needs. 3. Easy Installation: The indicator adopts a user friendly design with three screw holes at the bottom of the case. This allows for easy installation on machine tool spindle chucks, with the dial facing the operator for convenient positioning and reading. 4. Precise Reading: This tool provides imperial measurements with a range of 0.12 inch and a 0.00000 inch display, delivering accurate measurements for your metalworking projects. Suitable for use on vertical or horizontal machine tools with motorized or manually turned spindles.