Highly useful tools for internal linear measurements such as measuring cylinders, rings, setting calipers, comparing gages, and measuring parallel surfaces. The extension rods are made of steel tubing, light in weight, yet extremely rigid. By removing the hardened and ground anvil ends (end caps) of the micrometer head, the rods may be attached to either or both ends of the micrometer as preferred. Each rod may be individually adjusted for wear by the hardened and ground anvil at the end. Insulated rods with the exception of the 1/2" and 1" sizes. Each rod marked with length.