St arrett Reliable Precision Micrometer Design and Manufacturing Fea tures Tapered Frame – a Starrett original feature – permits measurements in narrow slots and tight places. Standard with Starrett. Ring-type lock nut convenient to use. Permits locking of spindle at any reading. Easy to read with distinct black figures against satin- chrome finish. Staggered graduations, advanced design, a Starrett original feature. Quick reading figures on inch reading micrometers. Every graduation numbered for quick, positive identification. Easy to read with distinct black figures against satin-chrome finish. Friction thimble, smooth uniform pressure independent of "feel." Ratchet stop/speeder for consistent measurements and to speed opening or closing of tool. Extra Hard Threads with Extreme Lead Accuracy. Special high carbon steel gives harder threads which are hardened, stabilized, and precision ground from the solid to ensure long and accurate life. Balanced design; plus no-glare satin chrome finish makes the tool easy to hold and read, as well as resistant to stains, corrosion and wear. Micro-Lapped "Mirror" Finish on the measuring faces – a Starrett original feature that ensures more accurate measurements. Available with carbide faces or hardened, high-carbon steel faces. 20 M icrometers