n.
In manufacturing and engineering , a device used to determine whether a dimension is larger or smaller than a reference standard.
A snap gauge, for example, is formed like the letter C, with outer "go" and inner "not go" jaws, and is used to check diameters, lengths, and thicknesses. Screw-thread pitch gauges have triangular serrations spaced to correspond with various pitches, or numbers of threads per inch or per centimeter. Deviation-type or dial gauges indicate the amount by which an object deviates from the standard.