Germany / Saar: Scarce overprinted 80 Pfennig Sarre Stamp on Cover

Scarce 80 Pfennig Germania stamp with Sarre overprint on cover, CTO.
Clean cover from 1920 in good condition.
The upper right corner of the stamp has a minor fault. (It rather seems that its because the paper is slightly uneven than that a tear exists).
( Michel DEM 2,500 after old Michel catalogue).