Picked this up in a huge jumbled unorganized group on insulators some years ago with no history known. It is solid lead in a Chester threadless design mold. Perhaps a private issue insulator but I am unable to find any info on it. There must be an old timer in the hobby that remembers when these were introduced into the hobby and by whom and for what purpose. Somebody spend a lot of effort on this and it is a quality reproduction.

Any help appreciated. Thanks so much!