A height gage does exactly as its name indicates—measures the height of a workpiece. A height gage is a measuring instrument in which a slider with a measuring stylus moves relative to a measuring scale on a beam and in which this motion is along a single vertical axis nominally perpendicular to a reference plane on the instrument base.
Height gages are normally used on a granite surface plate to measure and/or scribe part features from a datum plane. Generally a scriber, test indicator, touch probe or CMM-style probe is used to locate the measured feature. Height gages are an indispensable instrument for quality control.