The designation master gage refers to the application of the gage and not to its quality level , although fixed gages in master gage applications are usually required in the highest accuracy grades. The specified accuracy of these gages, however, may be regarded as a consequence of the particular function that the master types of fixed gages are expected to perform.
Master gages are used in many diverse applications , but none of these comprises the direct measurement of production parts. Master gages are reference standards , used for setting, checking , adjusting or calibrating the limit types of fixed gages.
For each nominal dimension one master gage is commonly used. There are a few exceptions to this general practice, such as in the case of certain types of air gages with adjustable amplification. In these latter uses, the master gages are required to be in pairs , or to be comprised of two dimensions, representing the setting range of a particular comparator iinstrument.