Just slide these collars onto an unhardened shaft and tighten the set screw to hold the collar in place.  Collars are easy to adjust, but their set screws can cause marring. They are not very effective on hardened shafts that do not have flat spots for the set screw to press against.

Steel Collars

Aluminum Collars

Clamp on collars allow greater holding force than set screw collars plus they will not mar the shaft. They clamp on evenly around the shaft providing excellent holding power. We highly recommend clamping collars over set screw collars.