A little side project I've been doing is gathering information and histories of some of the modern insulator manufacturers and importers in the U.S.A. There are only a small handful of porcelain insulator manufacturers in the U.S. most of the insulators are imported these days. I think these markings on spools are pretty neat. Top Row Left to Right: Seves Corp (PPC Insulators), Santana Insulator Co., Hubbell/ Chance, MacLean Power Systems, Tiffin Insulators Co., GPP (Grid Power Products), PLH Powerline Hardware Co. (Guy Wire Strain). Bottom Row Left To right: VI (Victor Insulators), Lapp Columbia, Gamma Columbia, CST (Ceramica Santa Terezinha). I have yet to find spools from these manufacturers but will keep looking. ICB (Industria De A Isladores Casa Blanca), CPS (Cooper Power Systems), ME (McGraw Edison Co.), BBC (Brown Bouvier Company), and NGK (Nippon Gaishi Kaisha) which translated stands for Japan Insulator Company. Thanks for looking. Take care to all.