1974-1991 SPECIAL SPECIAL ENVELOPES / comp. 8 pcs of off. envelopes without printed stmp., i.a. 20. Anniv Czechosl. federation - incl. PF, Prague castle - incl. PF, Europe in space - CEPT, World post únia 1874 -1974, Coach and 2x small envelope with additional-printing detail stamp. Pigeon-issue in/at blue and red color; good condition