The Three-cent Prexie
Multiple lower rates
A very unusual use of a certificate of mailing form in 1946 to show that three items were mailed, and marked as a duplicate as well. From July 1, 1929 until July 1, 1957 the cost of a duplicate certificate of mailing was one cent.

Foreign mailing of printed matter using a three-cent Prexie. There was no general printed matter rate of three cents, so the postage would likely be for a periodical between 2 and 4 ounces at one-and-a-half cents per two ounces. This rate was current from April 1, 1932 until November 1, 1953.