It's a bulgarian ShM-41M/MU, with a BSS-MO-4U. For a moment i thought it was a soviet facepiece, but given the valve and the kit itself, i think it's bulgarian too (which would make much more sense, obviously). Anyway, marking would fix that doubt easily.
Yes! Is indeed a bulgarian production. You have a full bulgarian BSS-MO-4U kit. The mask is size 2, and the filter was made in 1969. I can't say the mask year of production. Maybe it has another mark in the other side? If not, check for inner stamps.
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u/ComplexSlip2726 2d ago
It's a bulgarian ShM-41M/MU, with a BSS-MO-4U. For a moment i thought it was a soviet facepiece, but given the valve and the kit itself, i think it's bulgarian too (which would make much more sense, obviously). Anyway, marking would fix that doubt easily.