There was a request for pictures of segment threads -- here are three examples of two, three, and four. I believe there was a question regarding the CD 187 with segment threads -- it would match the two segment example. There was one of these for sale at the recent Metroplex show.

The insulators shown are as follows (Left to Right): -- CD 110.5 NAT [040] - National Insulator Co. -- CD 136.7 POTH [010] -- CD 158 BOS [010] - Boston Bottle Works