The Starrett 224AARLZ interchangeable micrometer has the following specifications: Range: 0-4″ Graduations: .001″ Standards Included: 1″, 2″, 3″ Anvil/Spindle Material: Steel Thimble Type: Ratchet Lock Nut Type: Knurled Ring Type Features: Suitable wrenches are furnished to make necessary adjustments Combination ratchet and speeder for uniform pressure and quicker adjustment Quick and easy sleeve adjustment Advanced sleeve design with staggered lines and distinct figures for precise and easy readability Balanced frame and thimble design ensure easy handling and better readability Rigid and stable special cast iron frame with appropriate perforations for lightness and ribbed for strength and stability Micro-lapped measuring faces Large thimble diameter with distinct figures Ring-type knurled lock nut for quick and sure locking Interchangeable anvils for diversified gaging Each micrometer is equipped with a series of easily interchangeable anvils, thus providing the full range in steps of 1″ with a single micrometer These larger sizes have .300″ (7.6mm) anvil and spindle diameters for ease of use on larger work Extremely hard and stable one-piece spindle Starrett No-glare satin chrome finish on thimble and sleeve minimizes annoying surface glare under bright lights and resists rust