A person contacted me about a piece. His description was
" Its about the average height of your average telephone insulator (all that without getting out the tape measure). I'm sure it would be classified as threadless.... as there is no place for a pin. It is egg shaped. It is 2 piece, that appears to be "glued" together with tar. The inside of this looks like is filled with carbon... but may just be tar staining. And it is "egg" shaped. The top of the egg is a "rest" for the wire, and down 2 sides of the egg are notches for a special "clip" of sorts to hold the wire in place. The bottom of the egg is very round, as it appeared that the cross arm that the insulator sat in was cupped out, and the insulator was ...... glued into the cup with tar?"
Sounded pretty strange, so I asked a question or two (and asked for photos!) As you can see, and he reported, it is all glass, pretty make clear glass. It has no markings on it.
He said someone offered him $400 for it years ago. Could be a one of a kind fish float for all we know ;-)
An additional comment: They found (if I remember correctly) 2-3 of these in a box. The patrol thought they were grenades (as when I received this, it was painted a brighter army green), so they confiscated them. I have since removed the paint.
So, they were painted green, either at the factory or later...