This tool is used for marking rings prior to setting. The ring is held between firmly between two cones while the exact rotation is regulated by the wheel with teeth. There are 14 wheels with 15 to 28 divisions. You mark the exact location of the setting using your flexshaft. The kit includes two guides for drilling 22.5º and 90º holes and three drills (0.8 to 1.2 mm). Helps you create settings that are evenly spaced. Eliminates errors.