With Fowler Inside Micrometer you are assured of smooth operation and stabilized uniform accuracy. The frame is specially designed to enable the micrometer to provide extremely accurate small internal measurements. • Satin chrome finish on barrel and thimble • Measuring faces are fully hardened, precision ground and microlap finished to assure exceptionally accurate measuring • Spindle threads are hardened and ground • Microfine graduations (.001" or .01mm) on a satin chrome finish permit easy reading • Ratchet stop thimble assures exact and repetitive readings • Easy zero adjustment on the sleeve • Meets or exceeds Federal accuracy specs • Includes a setting ring • Includes a spanner wrench and a case