The Starrett 224, 224M 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 300-400mm 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: 300, 325, 350, and 375mm. 300-400mm, 0.01mm Grad.