Micrometer are widely used in various engineering settings for
measuring thickness of blocks, diameters of shafts, and depths of
slots, calculates even smaller dimensions than the vernier
caliper. Next to the caliper, the micrometer is the most
frequently-used hand measuring instrument. Micrometers are made in
various sizes and shapes, depending upon the purpose for which
they are intended. Some micrometers are graduated to measure in
thousandths of an inch, while others will measure as close as
ten-thousandths of an inch. Other micrometers are able to measure
in hundredths of a millimeter.