Here are the R-4 pieces I have. Left to right:Continental Rubber Works/Erie. Pa. U.S.A. Back Patent Pending (all small Letters), Front Same (Large Letters) Back W.U.Tel. Co./ Pat. Pend. Next Front and back same except Pat 3,061,667. Next one; Around top- Continental Rubber Works Pat 3,061,667/Erie Pa. U.S.A. (all small letters). Last one Front Continental Rubber Works/Erie, Pa. U.S.A. Back Pat. 3,061,667/Pat 2,504,483 (all micro lettering). Would love to find the Mexico marked Continental R-4.