This is a copy of a Moore Tools boring head. The divisions on the dial read in .0005" increments. This unit can adjust from zero all the way to 3/4" diameter. It has a 3/4" shank and there are two collets, a 1/4" and a 1/2" collet. There is also a set screw to lock the slide for rigid boring. It comes with an offset chamfering tool that is mounted in a 1/2" collet.