The author traces the development of the Hans Hass Rolleimarin system based on correspondence between Hans Hass and Franke & Heidecke from 1949 to 1955. The correspondence is said to be in the Hans Hass Institute. The author outlines the chronology of Hans Hass' post-war diving expeditions. The PR229 prototype was evaluated by Hass and wrote a six-page commentary on July 29, 1952 on the features of construction.