Original electrical trade vintage catalog for ARMSTRONG CORK COMPANY, of Millville, NJ. Manufacturers of Glass insulators, meet or exceed specifications. Each run is given thermal shock tests and polariscopic examinations. Made in brown and clear glass. Disbound from a large 1951 architect construction materials book, this unique old one page technical specifications brochure would display wonderfully matted and framed. A marvelous addition to your retro electrical equipment library.