The Starrett 724, 724M Series Tubular Bow Type Micrometers with Interchangeable Anvils are made for better precision measurement of large outside dimensions. These micrometers provide perfect balance, sensitive feel, ease of handling, and less measuring effort due to their advanced tubular design. The micrometer's tubular frame provides light weight, extreme rigidity, and standard coefficient of expansion. The 724 series is well suited for diversified gaging and provides a wide range of measurement in steps of 1 inch or 25mm. This model includes these standards: 25", 27", and 29". 24-30" Range, .001" Grad, with Lock Nut, in Case This model includes these standards: 25", 27", and 29".