A 7-inch (17.78 cm) by 9-inch (22.86 cm) black rubber gas mask. The Mark IV was the first mask made entirely in Canada with rubber from Goodrich Rubber. On the Eve of the Second World War, Canada produced enough masks to supply other Allied nations with anti gas components. The production of the mask was likely begun production in Canada around 1940 and was used until the end of the Second World War. An important part as a boost for the entire Canadian manufacturing industry.