This item showed up in a collection that had been boxed away for 20+ years. Patent Insulator? There is a 1" diameter collar and then it reduces to 7/8" It is 1 1/2 " long. I just don't know. I have had other patent models and the wood mounting seems about right. I would appreciate some help. If you don't know what you are talking about, please don"t comment. I know some of you do have patent models. Like to hear from you.