Specifies the dimensional, functional, and quality characteristics of micrometer callipers for external measurement. It applies to micrometers with a screw having a lead of 0.5 mm or 1 mm, having a maximum range of 25 mm in capacities up to 500 mm, and having non-removable anvils with flat measuring surfaces. Annexes give information concerning values for the error of measurement at any point in the measuring range, and recommendations for using an instrument and determining its accuracy. It is identical with and has been reproduced from ISO 3611:1978.