Canal Zone January 23, 1917, 12c S.S. Panama in Culebra Cut (#49) with Nov. 13, 1921, 2c Land Gate (#61) tied by fancy mute killers on legal size REGISTERED cover with blue Registry Mark (RM-4) and Balboa Heights (8-30-22, Rg-17), Cristobal (8-31, Rg-20), New Orleans (9-5) and two different Detroit (9-7 & 9-8) Registry backstamps. Stamps are Very Fine with vibrant colors. Exceptional Example of this Scarce Registered Usage!