Fowler 1-2" Inside Micrometer 52-243-012-1 Series No. 52-243 are extension rod type inside micrometers and have the shortest measuring length of their kind. The detachable handle offers the operator convenience and ease when using these small inside micrometers. Lightweight, rigid and well balanced. To achieve optimal accuracy, each set includes a micrometer head and two extensions, detachable handle, wrench and a deluxe fitted case. Fowler recommends that the inside micrometer with a rod be calibrated by a micrometer or ring gage. The anvil and spindle are hardened and precision ground. Spindle threads are hardened and ground. Microfine graduations: .001" on a satin chrome finish permit easy reading. Quick easy zero adjustment on the sleeve. Accuracy = .0003"+(.00005" x L"/2) Meets or exceeds Federal accuracy specs. Includes case