Gas Mask King
Belgian BEM 4 GP
The Belgian Engicom Mask, 4th generation, General Purpose (BEM 4 GP) had an adjustable inlet, allowing for three different filter positions. This example was made by Engicom in 1991.
Similar masks in my collection: Italian C60
Rubber stamp
Date stamp on head harness "4-96"
Animation
Line art animation demonstrating the three possible filter positions