Canal Zone, 1904, 8¢ violet black, in combination with 1904, 1¢ green + 2¢ carmine on Royal Mail Steam Packet Co. seal cover (backflap) to Costa Rica, each tied by violet "Colon, Agencia Postal Nacional, Nov 1, 1904" cds and Flag duplexes, receiving backstamp; couple small sealed cover tears at top, still Very Fine and attractive, a very rare 8¢ usage. Scott No. 7+4-5  Estimate $300 - 400. $0 (Image)