Bore gages are comparator type instruments used to compare parts being manufactured (unknown sizes) to known dimensions. "Setting" the bore gage to a known dimension requires the use of a reference master. The master ring is the most common type reference master used in industry and each ring is limited to one specific hole size. This means that a master ring inventory can reflect a large investment. Dorsey’s adjustable bore gage setmasters maintain all the advantages of master rings, but provide the added feature of adjustability. Within the specified capacity of each Dorsey "Setmaster", any dimension can be set by easily adjusting the master to a preset combination of gage blocks.