CZL propeller in one of the early version decal. Produced approximately around 1921-1922. Attached to the engine (yet unknown type), used for training. Picture taken in Bydgoszcz, at the School of Aviation Mechanics, (1922-1923). At the background hangar with characteristic folded doors – most likely one of these taken subsequently to Dęblin (these hangars are used till today!). Picture received from Robert Gretzyngier.  Many Thanks!