Hey I forgot about the tennis balls. They do work just great. I had to use them in my classroom on all of my students' chairs when I had a deaf child in the classroom. She could hear just a little and the chairs scooting around on the tile floor really bothered her. Since no carpeting, HS tennis coach gave me enough old tennis balls to use on every chair in the room. It worked wonders. I kept them on my classroom chairs for years.You would not believe how nice and quiet it was. Just wish I had known about it years before.