The fuselage structure was fabric covered welded chromium-molybdenum steel tubing, the biggest difference between the Fokker and the Morane, which had an entirely wooden framework.

Subsequent production E.Is had their wings lowered slightly – as Leutnant Otto Parschau's E.1/15 had later in its career during 1915 – from the M.5's shoulder configuration, which improved pilot visibility.

Wintgens is known to have downed a two-seat Morane-Saulnier Type L parasol monoplane on 1 July 1915 while flying his M.5K/MG, but as the victory occurred in the airspace behind Allied lines, over the Forêt de Parroy near Lunéville, this could not be confirmed at the time.

The M.5K/MG usually used the Parabellum MG14 machine gun for the synchronized armament, which could prove to be a troublesome arrangement, and the five M.5K/MGs built by the Fokker factory in Schwerin/Gorries retained the "shoulder-wing" position of the M.5k for the monoplane wing.

E.Is were mainly flown by regular pilots of the Fliegertruppen des deutschen Kaiserreiches, with one Eindecker attached to each six-aircraft Feldflieger Abteilung aerial observation/reconnaissance unit.