On December 1, 1929, the treaty rate for 20 g letters to France was increased to 1.25 F. This rate remained in effect until the German occupation rates took effect on October 1, 1940.
Here the rate is paid by a combination of the 1929 Princess Marie-Gabrielle Caritas semi-postals. The unusual franking comprises the 75c, 35c, and two 10c stamps from the set, overpaying the rate by 5c. Issued on December 14, 1929, these were the first stamps to appear after the 1.25 F rate took effect.
This commercial cover was posted from Luxembourg-Gare [B], January 8, 1930, to St. Étienne de Rouvray near Rouen in the Seine Maritime Department. Non-philatelic uses of the Caritas semi-postals are always difficult to find, especially so for this issue.