Courtesy Swedish Historical Diving Society, photo by Åke Larsson.
For pictures about the SM 1 unit check out Åke Larsson's SM 1 photo page :
http://www.teknosofen.com/draeger_sm_pic.htm
The wiring is the elektrical connection to the lamp in the mask for guarding the gas flow.
Courtesy G.Haux (note: counterlungs are not situated in this way with the SM1)
Courtesy G.Haux
