Elbow; I'll tell you what I use and it seems to work fairly well. Go to the hardware store and look in the section where they have the caulking guns (may have to ask?)I think they are made by Red Devil,they are for putting over the tip of a caulking tube once they are opened. they look like small doughnuts and roll on and off much like the larger birth control devices if ya know what I mean! I had some in my shop and one day thought---HMMMMMM.... I wonder if they would go on the tip of my bow and protect them? Well they roll right on and seem to work ok. Lots of them in the puck shaped can and if you loose one or it wears out,put one on again!They are red but you can't tell much they are there due to the size.They are thick enough to do the job but also lite enough not to hurt your tune or anything. Works for me! Other wise you can go to *******.com and a guy has a build along for the leather ones.