This Mandrel has a 3/8"x16 self tapping screw that cuts threads into the wood blank. This makes it easy to mount the the finished turning on the bottle stopper stud. The mandrel fits in a #2MT of the headstock and is threaded for a user-made 1/4"x 20tpi draw bar. It can be held in a 4-Jaw Chuck. An 11/32" drill bit must be purchased to make the pilot hole for the mandrel.