A while back I was lucky to acquire a CD 140.5 insulator... these are thought to be related to the EC&M insulators, and to my knowledge have only been found in California and Nevada. They also have a large "dot" on the front, very similar to EC&M insulators. They are a bit of a mystery though, and their exact use is undetermined. One odd characteristic is that the pinhole is not a standard size, it is oversize and very short. For a look inside [id=348775113]