I don't know how I ever threaded my sergers without these.  They're the best I've found.  They are lightweight, and hard to see; so they're super easy to lose. I'm ordering more because I've already lost three; it's kind of like keeping track of a spider's leg. I need to be more careful with them.  That said, if I had to use a new one every time I threaded my serger, it'd be worth it.