U.S. Scott 825 and 804 Prexies/Prexys paying the 3 cent first class rate on a reused window envelope that had previously been mailed with Scott 852, issued for the Golden Gate Exposition. The letter was mailed from Trenton, New Jersey to Hercules Leather Goods Co. in New York City on April 19, 1939. Cover was roughly opened at top (see scans).