>>826205A swivel allows the lure and rigging you made to remain properly aligned. It allows spinning without torsioning your fishing line.
A snap swivel does the same thing, but also allows quick lure/hook changes.
It isn't meant to be used as a stopper. Instead you actually use a, "rubber line stopper," or "stopper knot," for that purpose. Neither of which cut the line or require a knot in the main line itself. They merely attach to the line. A, "stopper ring," can be used but requires the line to be cut and tied to it.
Using swivels for stops when they are not needed in the rig just puts unnecessary knots in your line.
