Outside micrometers. Features: 1) Graduation: 0.0001" / 0.01mm Outside micrometersFeatures:1) ... , 1 - 2"/25-50mm, 2 - 3"/50-75mm, 3 - 4"/75-100mm, 4 - 5"/100-125mm, 5 - 6"/125-150mm, 6 - 7 ... .01mm2) Range: 0 - 2"/0-50mm, 2 - 4"/50-100mm, 0 - 4"/0-100mm, 4 - 8"/100-200mm, 0 - 6"/0-150mm, 6 ... -25mm, 1 - 2"/25-50mm, 2 - 3"/50-75mm, 3 - 4"/75-100mm