Signedplate on top of lid: OWEN BRIDGE / TYPE NO. P-508 SERIAL NO. 102 /
(GR logo) / GENERAL RADIO CO. / CAMRBIDGE, MASS., U.S.A. / U.S. PATENTS
etched and white filled on top panel: OWEN BRIDGE / TYPE NO. P-508 SERIAL NO. 102 / GENERAL RADIO CO. / CAMRBIDGE, MASS., U.S.A
plate on side: (GR logo)
Inscribedstamped in white: NDRC / 658 / 1782
stamped in yellow on side: ACCOUSTICS
in red on side: OWEN / BRIDGE / (Inductance)