SPI Tube Micrometer with Barrel Anvil Designed to measure the wall thickness of various tubing. Features Include... 0-1.0" Measuring Range 0.0001" Graduations + 0.0001" Accuracy 0.137" Barrel Anvil Diameter 0.250" Spindle Diameter Carbide Tipped measuring faces Ratchet stop Painted frame with heat shield Lever lock Fix anvil length: 0.315" / 8 mm Includes Certificate of Calibration Furnished in fitted case