It's a failed secret project of chemical weapon: i look like an accordion, but it is full of chemical agent.
Once dropped behind the enemy's line, they assumed that the bored germans will try the instrument, unwillingly killing all the soldiers around.
Testing revealed the "project accordion" to be efficient but also revealed that the soviet standard gasmask have some major flaws so they cancelled the whole project, fearing that knowledge of the gasmasks problems will dangerously affect the morale of the nation...