Cover with manuscript 'Correo Aereo' on front franked with 1921 5c brown and 1921 25c brown 'CORREO AEREO' airplane overprint issue with overprint in green (SG 387 & 377) tied by MONTEVIDEO cds dated 22 JAN 1923. Flown on the Special Montevideo - Buenos Aires, Argentina flight commemorating Shirley Kingsley, the winner of the air race between the two countries. Arrival marks on reverse. Rare. (Muller #6b, only 185 covers carried)