Russian/Soviet Маска Мембрана 1 (MM-1)
The Russian/Soviet Маска Мембрана 1 (ММ-1) was very similar to the Шлем Маска ШМ-66Му, but had forward-facing eyepieces, and used a five-point head harness instead of the helmet design. This example was made in Moscow in 1974.
Маска Мембрана = "Mask Membrane"
Шлем Маска ШМ-66Му = "Helmet Mask ShM-66Mu"
Similar masks in my collection: Russian ShM-66Mu