Micrometre
The micrometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known by the previous deprecated name micron, is an SI derived unit of length equalling 1×10−6 metre (SI standard prefix "micro-" = 10−6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.000039 inch).
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