Here is a line up of the Continental R-5 and R-3 pieces I have. Left to Right: Top R-5 Front- Continental Rubber Works U.S.A. Back: Pat. 2,218,497/Pat 2,504,483. Next same front/top Back Patent Pending. Top R-3 Front Continental/Rubber Works U.S.A. Large Letters Back W. U.Tel. Co./ Pat 2,218,497. Next Front and back same except Pat. 3,061,667. Last Front back same except Pat. Pend.