Airmail cover franked with 1923 10c carmine, 1929 pair 5c on 2col rose red plus 1930 10c carmine and pair 20c on 50c ultramarine 'CORREO AEREO' surcharge issue (SG 143, 172, 181 & 183) tied by TURRIALBA cds's and CORREO SEREO COSTA RICA cds's all dated JUL 27 1931. Addressed to CZECHOSLOVAKIA. A nice franking.