Shown above is a page from the 1908 Union Electric Cataloug owned by Elton Gish The catalog listed Lima insulator co products. The big surprise is the listing of an insulator described as a "ring top" at the bottom of the page. Clearly this is the basic design in the U-339 series !!! The the exact insulator shown has not been reported and would be a super find if any ever turn up . the description shown clearly explains the use which makes sense as leads into transformers would want to allow a bit of flexibility for transformer servicing and replacement . if a no-tie design is used the conductor can be pulled back through the loop to allow easy removal of a transformer without needing to untie the conductor. The U-339, 339a and 339b [id=295261829] are all insulators that seem to fit this description well and likely they were all made for this specialized use as no- tie jumper holders. I guess we need to start calling them "ring top" insulators rather then loops. I wonder if this was a Fred Locke idea???[id=265062845]