These photos were sent by Hans Weber. They were taken at the Fliegermuseum in Duebendorf, Switzerland.
Knut Erik Hagen adds:
Six Hafeli DH-1s were flown 1916-19, the one on display is a replica. Constructor August Hafeli had been employed in Germany at the Otto works and the design resembles AGOs C.1.
Other Hafeli designs include the DH-3 two seat observation plane of which 110 were built between 1917 and 27 and its replacement; the DH-5 of which 60 were built -the Fliegermuseum is supposed to have a replica with some original parts.