Cover with boxed 'POR AVION' in red on front franked with 1921 25c brown 'CORREO AEREO' airplane overprint issue with overprint in green and 1923 'Battle of Sarandi' issue set of three (SG 377 & 433/435) tied by SARANDI GRANDE cds dated 12 OCT 1923 and also by commemorative cancel. Flown on the Special Sarandi Grande - Montevideo commemorative flight. Addressed to MONTEVIDEO with arrival cds on reverse. (Muller #7, 880 covers carried)