Soviet Model 1936 Infantry Pack.  This piece is offered as a restoration project to an ambitions reenactor…  hopefully.  What you see is what you get, a well used backpack, missing the shoulder straps and a few other bits.  Someone handy in leathercraft could turn this into a useful piece of kit.  One tip to offer is that the toggle bolts used to secure the shoulder straps to the pack body on the German version of this pack will also work on this one.  They are a lot easier to find.