[Coaxial Concentrous Index Set] The central dial test indicator is a new measurement tool. Use the relative position of the workpiece center to transmit the relative position of the workpiece center to the dial indicator and convert it to pointer angle displacement.This is an accurate, convenient and visible tool. You can find the relative center of the processing workpiece, such as the circular and internal holes of the processing workpiece. Color: As Shown Material: Metal Package Contents: 1set x dial indicator Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.