Starrett 823EZ Tubular Inside Micrometer Set, 4-to-40-Inch Range [Misc.]Features thermal insulators on each rod. Satin chrome finish on heads - no glare, resists rust. Each rod marked with length. Hardened and ground anvils on rods, adjustable for length - head anvil hardened and ground. Quick reading figures - every thousandth numbered. Quick easy adjustment for micrometer screw. Tubular measuring rods - light weight plus extreme rigidity. Rods attachable to either or both ends of head - ensures the best balance, feel and ease of reading. Lock nut furnished on 1" heads. Interchangeable anvils on both 1/2" and 1" heads.