Unknown Romanian, possibly industrial, mask. It is the only one ever found and what makes it special is the valve asembly, it is quite similar to the polish (old) MP6. : r/gasmasks
GAS MASK MODEL MP-6 WITH FILTER – Products - Maskpol - producent sprzętu ochronnego dla Wojska
Maska p-gaz MP-6 + instrukcja w Mundur w MyViMu.com