The gaging setting standard is one of those metrology foundations that does not get much respect. These typically take the form of a master setting ring, disc, or plug. Take, for example, a 10mm master setting ring. One can purchase a 10mm master ring, class XX, for about the same cost as a high-quality digital caliper.
Because of its nature, a digital caliper is one of the most universal measuring tools, making direct reading measurements anywhere over its 150 mm measuring range. In contrast, a master setting ring is good for one setting – the size it is manufactured to.