Starrett 684M-4Z Millimeter Reading Internal Chamfer Gauge With Yellow Dial, 90-127 Degree Angle, 25-50mm Range
These gauges directly measure the diameter of chamfered holes. No setting master is necessary. When the three-blade plunger is pressed against a flat surface, the gauge should read the set number stamped on the back of the indicator. In case of wear, the gauge may be adjusted to read the proper number.