Larger than 20 microns or smaller than 20 microns; know if your product will sift.
Commonly used as shorthand for micrometer, a micron is the measure of length universally used to describe tiny particle size. The official symbol is μm, although it’s acceptable to simplify as um. A micron is a unit of length equal to one-millionth of a meter, a little more than one twenty-five thousandth of an inch. The naked eye can generally see particles larger than 40 microns.