The dial test indicator is much more accurate than a dial indicator, but over a much smaller range of travel. A test indicator measures the deflection of the arm, the probe does not retract but swings in an arc around its hinge point. It measures to 0.0005” but travels only 0.030” (0.015" from the zero point in either direction). You can indicate on the inside walls of a hole, which cannot be done easily with a standard dial indicator. The tip rotates a total of 240º (120º from zero in either direction) for flexible setup. Useful for turning and milling operation. Includes fitted case and two fixtures for mounting the test indicator; easily attaches to Smithy's magnetic base, 20-000 or to the Mini-Magnetic holder 19-011.