The Mitutoyo 122 series blade micrometer has a vernier scale in metric units for taking precise outside diameter (OD) measurements, and a blade anvil and spindle for measurement of groove diameter of shafts and keyways. The spindle does not rotate during adjustment, to help provide steady positioning for measurement.The micrometer’s frame is made of high-grade tool steel for durability. The vernier scale on the thimble and sleeve is graduated to 0.001mm, and has a satin chrome rust- and glare-resistant finish. Depending on the model, the spindle and anvils are made of hardened steel for durability or are carbide-tipped for wear resistance. Micrometers that measure greater than 25mm come with a standard bar for zero-setting. The unit comes with a fitted 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.