First Day of Issue = April 20, 1945
Size: 30.50 mm x 25.00 mm
Perforated 10.00 x 11.50

Used in the German held enclave Kurland from April 20, 1945 until May 8, 1945. Overprinted and surcharged German Feldpost stamp.

Catalog numbers
Scott 1N24
Michel DE-KU 4B

For more information check out the links below
German Feldpost stamps
German occupation of Courland