Mich. Comp. Laws § 290.604

Sec. 4. The state reference standards shall be maintained traceable to the international system of units through calibrations by a national metrology institute and shall be kept in a safe and suitable place in the weights and measures laboratory of the department and shall be maintained as recommended by the NIST handbook 143, which is incorporated by reference, unless otherwise noted. The state primary standards shall not be removed from the weights and measures laboratory except for repairs or certification. The state primary standards shall be used only to verify the secondary standards and for scientific purposes.