Extremely scarce cased Kriegsmarine optical gasmask

One of the rarest gas masks out there; the Kriegsmarine optical communications gasmask or Optische Gasmaske M-44. This gasmask is only scarcely seen and was issued to troops operating gunsights or range finders. The gasmask is in good supple condition and comes with the air hose that connects to the filter. The mask alone is incredibly hard to find; finding the accompanying case with accessories is even harder. The case comes with the manual in the lid and the tool to set the eyepieces. The case is marked 3,7 on the bottom most probably indicating a certain 3,7cm Flak gun on a ship or emplacement along the Atlantikwall. Super scarce piece in great condition!