This isn't the proper term for what I need. I have used these in the past to make mounts in stem cap openings. Here is what I need. There are 2 washers and a rubber or silicon bushing. All with the same outside diameter with a hole in the center for a bolt to pass through them all. One of the washers has a solid mounted nut on it. So when you tighten the bolt the two washers come together and squeeze the rubber\silicone part and expand it. I need this because a set of handlebars I have only have one end threaded for a bar end weight, I was going to use one of these to put a bar end weight on the other side. Anyone know what I'm talking about? Or should I just make one myself...if I can find a piece of round rubber . Certain bar end mirrors use this system as to certain GPS mounts that mount to the hole under the stem cap on top of a triple tree.