Rare Glass Insulator- Experimental Hemingray, CSC, clear glass. 1930-1950

Collectible Glass Insulator Experimental Piece- Hemingray, CSC, 7-49, CD128, O45 clear glass with metal bushing threads inside. They did this as an experiment to see if it would work better than putting the threads right into the glass. Rare to find! 1930-1950's