The previous photo was in black and white to compare it to the photo in the book. I helped Dwayne Anthony recently purchase the Milholland collection, and Dwayne knew this was something different! Likely a Hemingray product. In appreciation for my assistance in his getting the collection, he gave it to me. Thanks Dwayne!
In Milhollands book they described it as
"This insulator has a slotted pin hole that carries through. The lower pin hole -- lower, based on the reading of the embossing -- is four segments."See the next several photos for more details. The piece is tending towards light aqua, and is embossed both above, and below, the wire groove with "PATENT/APPLIED FOR". It is 3 inches in diameter at the bottom, slopes up to 3 1/2 diameter at the top, and is 3 1/4" tall
CD 1025 lives again!