Canal Zone first day cancel handstamp
The Canal Zone Postal Service (CZPS) managed the transportation and distribution of mail within the U.S. Canal Zone. It also issued postage stamps. This "first day of issue" rubber postmarking device was used for a new issue on April 19, 1976. The CZPS ended on September 30, 1979. Imprints of this device are known on covers. It was used for the booklet pane of the Dredge Cascadas and is listed in the Scott Specialized Catalog under #163a.
The device was used at the Balboa first day ceremony to postmark envelopes bearing the newly-issued stamp. It is typical in design and construction to "first day of issue" postmarkers used in the U.S.