Spare filter for Volksgasmaske 37 civilian gas mask, of German production, dating back to the Second World War. Consisting of a sturdy ribbed aluminium cylinder, with screw joint and perforated bottom, the filter, a produce of the Auer A.G. plants of Oranienburg, near Berlin, contained two cotton laps, held in position by a thin metallic net: at the center, an activated charcoal layer assured an effective defense against chemical weapons, performing a useful smoke absorbing function as well. Besides check embossings by the state authority for the inspection of air-raid defense devices (Reichsanstalt der Luftwaffe für Luftschutz), namely «RL1 38/4» and «5 125», the top of the filter shows some ink stamps relating to the production lot, «029» and «0388», in addition to the «Wa.A. 320» WaffenAmt code. Fund of store, the piece suits well for the placement in a collection dedicated to the German air-raid protection in the 1939-1945 conflict.