This is one of my favorite Neon sign insulators. A lot of times it comes up as a whatsit that someone found in a collection or flea market etc. Besides resembling an old multipart insulator they are unique in usage and attachment to a sign. Patented by Lewis F.R. Bellows 2,173,510 Sept 19,1939 these neat little insulators use a clamping system with rods and a spring ring with a copper tube holder for the glass tube to excite the Neon gas inside the tube. The top picture is of two that are in my collection. One is chocolate brown and the other dark brown. I used a wall tube to show how the neon tube would sit in the spring ring. The bottom picture is of the clip mechanism that holds the insulator to the sign it also shows the copper cup that sits in the spring ring for the neon tube. This was on an auction and went for a high price. i wish I could have purchased it because you never find the fastener clips on the bottom let alone the copper cups. At least I was able to get this picture from the internet auction to keep for my reference. The next photo I posted shows these in use on a sign.