Here is an insulator with a distinctive shape! CD 259 CABLE in a light aqua. The inside of the inner skirt is threaded for the purpose of screwing on a dual threaded pin if my guess is correct. There are (2) day 1 open bubbles side by side on the base edge that left a small shard type flake to one side of the bubble. The rest of the open edges are rounded. I detect just a couple other tiny blemishes and fleebites. No chunks or cracks and displays mint. First mail to me... Extra info given to me... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The outer threads were patented by S. Oakman as a further spacing between the wire and the pin in order to further reduce leakage. For efficiency (simplicity) of mold production glass, a screw-type threading was selected, even though it does not correspond to an actual applicable pinning mount mechanism. $35 + actual shipping.