WW2 model Finnish gas mask bag, originally designed for home front and rear units, however, these too saw action up at the frontlines (see the last photo, source: SA Kuva). And if carrying a gas mask isn't your thing, this works well as a general-purpose shoulder bag.

The flap is secured with buttons or two leather straps, this varies from bag to bag. The shoulder strap is adjustable. Fits A4 sized papers and books.

Used condition, made somewhere between 1939 and God-knows-when. Still in perfectly serviceable shape!