Some systems only have the ability to clamp milling tools directly into the rotating spindle. Stop rings are necessary in these cases. By means of these rings, the length of the milling tool can be determined mechanically by the user outside of the spindle. We offer a range of limit stop rings varying in size from 3mm to 6mm in diameter and made of synthetic, brass and even a steel one with a locking ring. An insertion tool may be required to set some stop rings.