Dremel #401 Mandrel for polishing wheels A shank with a threaded head. 

It is used primarily with polishing bits and accessories

TIPS
- For best results, insert the mandrel all the way into the tool and then back it out slightly before tightening down.

This provides plenty of shank for the collet or chuck to hold onto.
- Simply remove the screw, line up a cut-off wheel or sanding band over the hole in the shank, and replace and tighten the screw.