1925, overprint AEREO CORREO 5c. and 20 c. with overprint inverted, unused with large part original gum, fine and rare, just 12 resp. 36 copies printed (Scott C2a, C6a)

1930, airmail, Herrera  5c. on 10c. , surcharge in yellow, horizontal pair, one with '1903' instead '1930', unused o.g., very fine and rare, just 50 copies printed, the variety being unique (Scott C21 var.)

1930, airmail, Herrera  5c. on 20c. , surcharge in blue, reading downwards, horizontal pair, one with '1903' instead '1930', unused o.g., very fine and rare (Scott C22 var.)

10 c.  on 20 c. with surcharge in violett, unused o.g., very fine and scarce, only 50 printed. (Scott C24)