Pre-war M/38 gas mask bag manufactured by Veljekset Åström OY.
M/38 gas mask was originally intended to be used by rear echelon troops, but ended up being the second most common gas mask type among frontline troops. It was a lot more portable than the most common M/30 gas mask.
There is a Veljekset Åström OY manufacturer stamp on the main flap leather strap.
The carrying strap has been cut, but an otherwise a good condition bag.
See photos for details.