The Mitutoyo 368 series Holtest vernier inside micrometer has three-point contacts for self-centering measurement of the inside dimension (ID) of bores, and a vernier scale in inch units for taking precise ID measurements. It also has a ratchet-stop mechanism that helps provide uniform pressure for precise, repeatable measurements.

The micrometer is made of high-grade tool steel for durability and has a satin chrome rust- and glare-resistant finish. The vernier scale is graduated to 0.0001” or 0.0002” depending on the model. The measuring faces are carbide-tipped or TiN-coated for wear resistance depending on the model. The micrometer comes with a fitted 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.