The BSS-MO-4U is the Bulgarian licensed variant of the ShM-41M.
Mask overview Edit
The mask is a typical helmet styled rubber soviet mask itself is called ShM-41M. With two circular eyepieces that can fit antifog inserts but it has also a Tissot tube system. The valves are made of metal which is painted dark green (the later ones were painted with transparent paint, so those are similar to the Polish SzM-41M) and has a 40mm GOST thread. The mask was made in 5 sizes.
The filter Edit
The filter itsefl is the BSS-MO-4u come in a light green-olive coloured flat box aluminium alloy canister with the same coloured cap (the filter is nearly identical with the EO-12) and a rubber cap on the bottom.
The first layer is special paper which filters out aerosols and dust, it contains 4-6% asbestos. The second is K-5U activated carbon with catalisator metal oxides (CuO, CrO3, Ag2O).
Bag and kit Edit
The bag is similar to the Soviet Type A bag, it is made of khaki canvas but it has no buckles.
The kit contained:
- ShM-41M facepiece (also called BSS-MO-4U)
- BSS-MO-4u filter (also called EO-24IX)
- Antifog inserts
CIA  datas about the mask from the Cold War.