Original electrical trade vintage catalog for PORTLAND-MONSON SLATE COMPANY, was located in Portland, ME. Manufacturers of electrical panels and enclosures, preferred by builders and buyers alike. High dielectric strength, durability, recognized as the slate of no surface leakage. Disbound from a large 1948 electrical construction materials book, this unique old one page technical brochure would display wonderfully matted and framed. A marvelous addition to your retro electric equipment library.