Fairly hard to find, I noticed in my collection, I had three different ceiling buttons. These were used to guide the wire at a half inch from the ceiling to drop for a cord or lamp attachment. I only found a couple of companies that advertised these with Pass & Seymour who had patented them. Here is three that I have The first two are Pass & Seymour and the smaller one a No Name. The P&S ones are numerously marked with the 2nd in the picture having two markings on top and one on the base. I guess they wanted you to know they were the ones who manufactured this. Pretty neat insulators anyways.