The thread is run between the slots to coat it. This makes sewing on a button easier, and it protect the thread from damage so one doesn't have to sew on the buttons as frequently.
Well, I finally found one of these available at JoAnn's Fabric. I paid $3.99 plus tax. Shame on me. I am going to lose my frugalista license. I was shopping at the Hobby Lobby for non-fabric-related stuff, and hanging in the beading aisle was the same device from a different company but for only $1.99. Both stores had this item in their beading sections rather than their fabric sections. Keep this in mind, as I will in the future.
