The Mitutoyo 511-444 Dial Bore Gauge for Blind Holes has a measurement range of 2 to 6" and is accurate to + or - 0.0002". It is precise to 0.0001" and can measure internal diameters at positions close to the bottom of blind holes. This direct-measuring gauge uses a two-point contact system to detect geometry problems such as ovality and taper, and carbide-tipped contact points provide extended wear and improved abrasion resistance. A rugged cover protects the dial indicator.

Bore gauges 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 gauges are typically calibrated with a setting ring and come in two types: simple and direct-measuring. Simple bore gauges are used with a caliper to transfer the hole measurement, while the more complex gauges take the measurement directly, and display it through a vernier, dial, or digital display. Bore gauges have a two- or three-point contact, indicating how many points on the gauge head touch the inside of the bore. Two-point contacts are better at measuring ovality, while three-point contacts are used to measure lobing or triangular form error. Pistol-grip bore gauges are used for fast, single-handed operation with repeatable results from one operator to another. Bore gauges can also be used in special applications, such as measuring threads, spline pitch diameters, and deep bores.

Mitutoyo manufactures precision measuring tools, metrology equipment, and related systems. The company, founded in Tokyo in 1934, formed Mitutoyo America Corporation in 1963 with headquarters in Aurora, IL.