By Dale Glendenning; posted April 27, 2014 View Original: Click to zoom, then click to magnify (1536 x 2056) 918KB
Found this at a flea market today. It's made of porcelain and has what appears to say NATIONAL INSULATOR on the front of base with a 21 below it and a patent date and number on the back. If any one knows anything about this please let me know.
