This is a view of the pinhole. It appears to be 1 3/4 inches across the threads. The insulator base is 3 1/4 inches across

The glass is a nice green, but not as dark as that usually found in French made Insulators. Thought to be possibly Swedish, Norwegian or Finnish.

Update:Fredrik Hojefalt advises that neither Sweden or Norway used glass for low voltage insulators, but Finland did. Does anyone recognize this insulator style?

Doug Netzke, [Sluggo] of Sudbury, Ontario has identified this as CD 405 from Germany Thanks to everyone for their help