Mitutoyo Tube Micrometer Designed to measure the wall thickness of various tubing. Specifications include... 0-1" Measuring Range 0.0001" Graduations + 0.00015" Accuracy Spherical Post Dimensions... 0.272" Bottom Post Diameter 0.315" / 8mm diameter Cylinder on Top Features include... Carbide Tipped Measuring Face Ratchet Stop for constant force Supplied in fitted case