The Brown & Sharpe outside blade micrometer has a vernier scale in inch 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 micrometers high-grade tool steel frame has a black 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 spindle and anvils are made of hardened steel for durability, and are lapped to help provide accuracy. A ring lock helps provide secure locking of the measurement position. The unit comes with a fitted wooden 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.Brown & Sharpe manufactures precision measuring equipment and metrology hand tools. The company, founded in 1833, played a key role in setting industrial standards in the United States. Brown & Sharpe was acquired by Hexagon Metrology in 2001, and is headquartered in North Kingstown, RI.