The top end of the screw has hexagonal tapered reception for the wheel to ensure no-slipping. This allows quick & easy repositioning of fly wheel and handle (3 tapped holes are ready for you to screw the handle into for maximum convenience and positioning while you use this tool).
Mild steel screw with heavy duty square angular thread and threaded die hole.
The adjustable clutch allows the fly wheel to stay put when you back it up. You don't have to worry about the handle spinning down on you while you change tooling. This is is done with the interplay of the two nuts on top of the ram. It is up to you to make this adjustment, but it can be done in a couple of minutes.