The Starrett 220M Mul-T-Anvil Micrometer with Round and Flat Anvils, Carbide Faced Spindle was a new development in micrometer design and patent is held by Starrett. This micrometer will handle a wide variety of measurements impossible to obtain with regular micrometers, such as measuring the wall thickness of tubing, cylindrical walls from a hole or slot to an edge, many hard-to-reach locations, and the thickness of screw heads, shoulder lengths, etc. A most interesting feature of this tool is that additional anvils of various shapes can be made up, and many of these anvils do not have to be hardened for that "special job". This micrometer can be furnished with .0001" graduations, but we recommend .001" or 0.01mm for easier and more accurate readings. The Starrett Company, with our years of experience, recommends this because the anvils on this type of tool are not backed up by a frame as in a regular micrometer and could bend slightly. 1", .001" Grad, Friction Thimble, Lock Nut, Carbide Spindle slightly.