Micrometer Type: Mechanical Minimum Measuring Range: 7" Maximum Measuring Range: 8" Graduation: 0.0001 Thimble: Ratchet Stop Accuracy: 0.00028 This micrometer is manufactured in a state-of-the-art ISO 9001 certified facility filled with modern machines such as Haas CNC milling centers, Brother CNC milling centers, Haas CNC turning centers just a few examples on the 50,000 sq. ft. CNC shop floors. Each micrometer is checked at 10 data points for maximum error tolerance with high precision gage blocks and also conducted inspection on parallelism and flatness by optical flat in a strict temperature controlled environment. The critical benchmark inspection media such as gage block are inspected periodically on world-known Swiss made calibration machines such as Switzerland’s Trimos’s Universal Gage Calibration System model Labortory500 and Germany’s Carl Zeiss Jena model 0-3000 mm calibration system for oversized length calibration. / accuracy of <0.3µm +(L(mm)/1200) µm / Baked enamel finished frame / Micro-lapped carbide tipped measuring face gives mirror finish on the measuring faces to make more accurate reading / Clear graduation on satin chrome finish on spindle sleeve to increase readability / Advanced spindle design in hardened and precision ground lead screw threads give reliable and accurate reading / Ratchet stop allows uniform pressure of spindle to the contact and enhance measurement repeatability