Air Post cover. 1921 (November 14), two stamps with violet line surcharge 30c on 50c green with additional clock seal ''12.30'' and date ''14. NOV. 1921'' affixed on reverse of cover to Medellin with additional franking by vertical pair of 3c green on front, tied by Medellin ''17. NOV. 1921'' blue boxed ds, some soiling, still F/VF, C.v. $1,150 as two used stamps off cover, Est. $600-$700 (Image)