[Coaxial Concentrous Index Set] The central 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 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, Manufacturer: Akfldms