Use this indicator to quickly center workpieces or fixtures on your mill. The measuring range is 0.25". The shank is 0.375" diameter and 0.75" long. The indicator is 5.5" long from the top of the shank to the bottom of the tip holder (the black part). Can measure internal diameters from 0.12" to 4.25" and external diameters from zero to 4...