Just a few decades ago, micrometers were considered the ultimate in precision for length measurements . Even the measuring machines used at those times in gage laboratories operated on the principles of micrometers.
More sensitive measuring instruments were developed to satisfy the requirements for higher accuracy , and they replaced the use of micrometers in many applications . Most of the higher sensitivity instruments, however, are of the comparator type, which require setting masters for referencing , possess only a reduced measuring range and are, to some extent , generally stationary .These , and many other characteristics , are definite disadvantages in comparison to the portable micrometer, with its capability of measuring actual lengths by direct indication over a substantial measuring range. In addition to these inherent advantages of the micrometer system and the relatively low price of the instruments , many recent improvements in the design and manufacture of micrometer gages contribute to assuring a continuing important role to this category of measuring tools in the field of length measurements.