The Starrett 469, 469M Series Large, Super-Precision Micrometer Head is our most accurate micrometer head. It is also available on special order with double graduations in red and black on the sleeve and thimble, permitting readings both ways with the spindle moving in either direction. This micrometer head has a 4-1/16" (103mm) thimble diameter and is graduated to .0001", .000050", 0.001mm, or 0.002mm for direct reading. It also has staggered graduations for easy counting and reading of lines. Spindle is carbide faced for long life. 0-25mm Range, 0.001mm Grad with Speeder, Carbide Face.