pins Similar to gauge blocks, these are precision-ground cylindrical bars, for use as plug gauges to measure hole diameters, or as parts of go/no go gauges or similar applications. Gauge rollers and balls These are supplied as sets of individual rollers or balls as used in roller or ball bearings or tool and die making applications. Calibration balls can be used to calibrate contact angle goniometers, CNC machines and similar equipment. See also Notes References . . Further reading External links The Joy of High Tech The Gauge Block Handbook; US National Institute of Standards & Technology (NIST) Monograph 180 with Corrections; 2004 Length, distance, or range measuring devices Metalworking measuring instruments Swedish inventions