The Mitutoyo 368-912 Holtest three-point micrometer set has TiN-coated points, a measurement range of 12-20 mm and is precise to 0.005 mm, with + or - 2 micrometers of accuracy. Titanium nitride (TiN)-coated measuring contact points offer durability and impact resistance, while the contact point geometry allows the instrument to measure to the bottom of a blind hole. The ratchet stop offers constant force for repeatability. Includes inspection certificate ensuring that the exact micrometer purchased has met National Institute of Standards and Technology master standards. This gage set includes two complete display units, setting ring, extension rod, and a fitted plastic case.

Bore gages measure holes, or bores, in a workpiece. They can measure the interior diameter of a hole at any depth, while internal micrometers can only measure to the depth of their teeth. Bore gages are typically calibrated with a setting ring. Bore gages come in two types, one simple, and the other direct-measuring. Simple bore gages are used with a caliper to transfer the hole measurement, while the more complex gages take the measurement directly, and display the measurement through a vernier, dial, or digital display. Bore gages have a two- or three-point contact, which indicates how many points on the gage head touch the inside of the bore. Two-point contacts are better at measuring ovality, while three-point systems are used to measure lobing, or triangular form error. Pistol-grip bore gages are used for fast, single-handed operation with good repeatability from one operator to another. Bore gages, regardless of type, can be used in some special applications, such as measuring threads, spline pitch diameters, and deep bores.

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.

What’s in the Box?

• Mitutoyo 368 series 12-16 mm three-point internal micrometer
• Mitutoyo 368 series 16-20 mm three-point internal micrometer
• 16 mm diameter setting ring
• Extension rod
• Inspection certificate
• Fitted plastic case