Respirator and haversack: khaki respirator mask with circular glass eyepieces and a central flexible ribbed hose that is connected to a metal filter cannister. The above are packed into a khaki canvas satchel.
First introduced in August 1916 and standard issue by the spring of 1917, the Small Box Respirator was the most advanced and practical anti-gas development used by British and Dominion forces in the First World War. The respirator consisted of a face mask with glass eye-pieces, and was connected to a metal 'small box' filter (containing containing active charcoal and granules) via a flexible hose. The contents of the 'filter box' 'afforded complete protection against the concentrations of different gases likely to be met in the field.' ('Military Operations. France and Belgium, 1916', Volume I, Brigadier-General Sir James Edmonds, Macmillan, London, 1932, p.80).
Worn on the chest in the 'alert' position, the haversack could be opened and the mask positioned for use with the minimum delay, thus saving valuable seconds during a gas attack. When in Marching Order the haversack was worn on the back, stowed above the valise.