Wide shoulder screw heads for better grip on your bits .
Mandrels for Dremel, Foredom, Sears(craftsman)Black and Decker etc. All 1/8" standard shaft size. Different screw heads to choose from incl: 1/16",1/8" and a rare 1/4". for use on attaching gear/bits for high speed rotary tools. Made of polished steel. Compare price to expense retailers. Note: picture shown is 1/8"X 1/4" screw head mandrel.
