Chod stoppers are designed to be placed on a lead free or leadcore type leader.
The base bead goes next to your lead set up, then your rig swivel and the the tapered sleeve (using a very fine baiting or splicing needle).
The slotted bead should be wetted and then slipped over the sleeve. 
In the even of aline-break this slotted bead will push off of the sleeve and fall away leaving the hooklink to slde freely up the the line. This e
will ensure the hooked fish isn't towing a leader and lead around.
 
with 25 in each pack these are great value.