Mitutoyo Tube Micrometer Designed to measure the wall thickness of various tubing. Specifications include... 0-25mm Measuring Range 0.01mm Graduations + 3um Accuracy Spherical Post Dimensions... 3.5mm Cylindrical Diameter 6mm Height of Measuring Cylinder Post Type "B" Features include... Carbide Tipped Measuring Face Ratchet Stop for constant force Supplied in fitted case