Universal backpack of the Soviet soldier. Materials: cotton tent fabric, steel buckle, wooden boss.
The word "sidor" call things that men collect when go to jail: a basic kit. At the heart of the design is a very old and reliable principle of tightening the neck straps. Such bags were used in the Crimean war and is used to present days (only the details change). Before the war it was officially replaced with the rucksack (mod. 1939), but remains popular due to simple and robust design.
It is possible to lose something from the Sidor only if it broke; but the untied bag falls down at once from shoulders.