The Serbian Заштитна маска М2 was an upgraded copy of the earlier Yugoslavian M1, itself a direct copy of the U.S. Army M9/M9A1 Field Protective Gas Mask.  This example was made by Милоје Закић in 1986.

Заштитна маска М2 = "Protective Mask M2"

Милоје Закић = "Miloje Zakić"

 

Similar masks in my collection:  Yugoslavian M1, Serbian M2F, U.S. Army M9, U.S. Army M9A1, Finnish M61, Swedish Skyddsmask 51, Swedish F2