Disc masters are widley used for setting comparators, adjustable limit or dial snap gages, micrometers, etc. and for periodically checking these settings. Disc masters are recommended for setting gages used to measure round work because the feel is the same for both setting and gaging. Disc masters provide a definite and unalterable standard for the particular job. They are available with gaging surfaces of hardened steel, chrome plate and tungsten carbide.