Cannister of Zyklon-B, which basically consisted of gypsum pellets infused with hydrocyanic acid (hydrogen cyanide).  This product was patented in the 1920s as a pesticide, and was extensively used in pest control and fumigation.  Unfortunately, a rather less worthy "dual use" was found for it in the 1940s ... Best regards, JR.

"Dual use product".

German infantry fighting in the ruins of Stalingrad (october 1942).

Stalingrad

A German gun crew in action during the suppression of the Warsaw ghetto uprising