The Russian/Soviet Шлем Маска Мало Габаритный (ШМГ) was the mask included with the Противогаз Мало Габаритный (ПМГ) kit.  It featured small round eyepieces for use with optical devices, a central speech diaphragm, and its filter attached directly to the cheek.  This example was made in Saratov in 1977.

Шлем Маска Мало Габаритный (ШМГ) = "Compact Helmet Mask (ShMG)"

Противогаз Мало Габаритный (ПМГ) = "Compact Gas Mask (PMG)"