The Starrett 224.1, 224.1M Series Interchangeable Anvil Micrometers feature a wide range of measurement and flexibility. Each micrometer is equipped with a series of easily interchangeable anvils, thus providing the full range in steps of 1" or 25mm with a single micrometer. This model features 16-20" Measuring Range. Smooth friction thimble for uniform pressure, the combination ratchet and speeder for uniform pressure and quicker adjustment, or a plain micrometer that depends on your own feel. Recommended for mechanics, automotive service and machine shops, toolrooms, inspection departments and wherever gaging involves a wide range of measurements.This model includes these standards: 16", 17", 18", and 19". 16-20", .001" Grad.