The Mitutoyo 123 series disk micrometer has disc-shaped measuring faces with flanges for measuring the pitch of gear teeth, a vernier scale in inch units for taking precise outside diameter (OD) measurements, and a ratchet-stop mechanism for uniform pressure during adjustment.The micrometer’s frame has a baked enamel finish for protection and durability. The vernier scale on the thimble and sleeve is graduated to 0.001”, and has a satin chrome rust- and glare-resistant finish. The diameter of the measuring discs is 20mm. A spindle lock helps provide secure locking of the measurement position. The micrometer comes with a plastic case for storage.Micrometers are precision measuring instruments that use a calibrated screw to measure small distances. These measurements are translated into large rotations of the screw that are then able to be read from a scale or a dial. Micrometers are typically used in manufacturing, machining, and mechanical engineering. There are three types of micrometer: outside, inside, and depth. Outside micrometers may also be called micrometer calipers, and are used to measure the length, width, or outside diameter of an object. Inside micrometers are typically used to measure interior diameter, as in a hole. Depth micrometers measure the height, or depth, of any shape that has a step, groove, or slot.Mitutoyo manufactures precision measuring tools, metrology equipment, and systems. The company was founded in Tokyo in 1934 and formed Mitutoyo America Corporation in 1963, which is headquartered in Aurora, IL.