One Micrometer Head. This is the Starrett Model No 663 micrometer head. This is used on machine tools, fixtures, special gages, and other equipment where micrometer accuracy in settings and adjustments are required. It has a total travel of 1", in 0.001" increments. This one has the spindle lock, and ratchet stop thimble on the end. 5" overall length. The nose mounting shank is 0.561" in diameter and 3/4" long. This one comes with the Ball-End adapter that is removable for standard ground end. This one operates smoothly. Pictures are of the actual item you will receive