.This insulator was catalouged by Locke in the 1910 era. This was a very specialized design. It was likely intended to support bus cables in power plants, steel mills, And other high amperage aplications. To date, none have ever been found in use. This piece is one of the few unipart insulators that have1 5/8" threads. If any saw service, they were likely cemented on to there pins. I know of only two of these odd things in collections .Both came from dumps in Victor . It is such a homely looking design, I nick named it" the toad"!!