Any of a number of deviation-type gauge s that indicate the amount by which an object being gauged deviates from the standard.
This deviation is usually shown in units of measurement, but some gauges show only whether the deviation is within a certain range. They include dial indicators, in which movement of a gauging spindle deflects a pointer on a graduated dial; wiggler indicators, used by machinists to centre or align work in machine tool s; comparator s, or visual gauges; and air gauges, used to gauge holes of various types.