Wire protectors (also called wire guardians or wire guards) are small, horseshoe-shaped findings used in jewellery making to prevent beading wire from fraying or breaking where it attaches to clasps or other findings. They’re especially helpful when using flexible beading wire like Soft Flex, Beadalon, Tigertail and Nylon.
 
Wire protectors help your jewellery last longer and give it a polished, professional look and they're especially useful when your design uses heavier beads or is intended for frequent wear.
 
How to use wire protectors:
Add a crimp onto your thread followed by the Wire Protector. To add the wire protector, thread the wire up through one side of the wire protector, around the U-shaped channel, and back down through the other side.
Attach to the clasp by sliding the clasp or jump ring into the loop of the wire protector (so it's sitting in the horseshoe curve).
Thread the wire back through crimp bead and pull everything snug but not too tight (you want a little flexibility at the connection) take care that you have pulled the thread tight enough so that you don’t have excess thread poking up out of the top of the wire protector.
Crimp the crimp using chain or flat nosed pliers. 
Add your beads.
To finish the piece of jewellery, repeat the process, by adding a crimp bead first, followed by the wire protector (don’t forget the add the second part of the clasp!)