Locate Workpiece Centre - Simple method of centering a workpiece, fixture or assembly Internal and External - Find the centre on internal or external diameters Easy Operation - The outer body and indicator dial remains stationary while the center spindle with the feeler attached rotates This allows the indicator dial to always face the operator. A retaining arm is included to hold the head in a convenient position Large Diameter Working Area - The combination of straight and offset feelers in different lengths allows a large work area to be covered, Weight: 1.0 pounds, Manufacturer: M-DRO