Dräger HSS (Heeres Sauerstoff Schutzapparat)
Undated postcard. Photograph taken by Walter Voight, Berlin-Steglitz; Sassnitz a. Rügen, Gardone-Riviera.
The Draeger Heeres Sauerstoff Schutzapparat was a closed circuit respirator. It was an improved version of the Draeger Tubben model 1914 and a direct copy of the Draeger devices used in mines before 1910. The respirator could function for three hours during rest or one hour when working as was described by the French "Services Chimiques" in 1916. It was also used on board Zeppelins.
Source: Imperial German Field Uniforms & Equipment 1907 - 1918. Somers.