On the back inside is a piece of paper that says: REL 2.0 VOLTS, P.U. 5.2 VOLTS, WKG. 5.2 VOLTS, REP. H.W.W.(someone's initials!), DATE 5-4-60, The metal name plate says: Union Switch & Signal Co, Swissvale, Pa. Made In U.S.A., D.C. Style H-H2 Signal, US Patents Re14940-1864224, Other Patents Pending, Patented In Canada 1919-1932, PC.242652 SER. L31109