Original insulation trade vintage catalog for LOCKE INSULATOR CORPORATION, was located at South Charles and Cromwell Streets, Baltimore, MD. Manufacturers of porcelain insulators, of every type, for all needs, from generating plants to service brackets. Locke switch, bus, pin-type, hi-top and bushings. Disbound from a large 1943 electrical construction materials book, this unique old two page technical specifications brochure would display wonderfully matted and framed. A marvelous addition to your retro electrical equipment library. Pages are detached and contains a small amount of residual glue on edge.