The gas mask is comprised of a tan-colored "stockinette" covering a rubber face piece with black rubber tube connecting to the metal filter container. The splinterless glass eyepieces set into threaded aluminum rims above an aluminum outlet valve and valve holder. Along the rear edges of the face piece are molded into the rubber six adjustable metal buckles into which pass the six straps comprising the head harness. These black, elasticized straps are threaded through slots in a black rubber head pad. This head pad is stamped in yellow ink "No. 4 Mk III", "Kaufman 10/41" along with a "C" broad arrow. The straps and head pad are in strong condition. Under the "chin" of the mask is also stamped with a "C" with broad arrow , Normal and a Lot number. "Normal" is embossed to the rubber to the interior of the nose, again referring to the size. The approximately 27cm long segmented connecting tube is crimped by wires to, at one end, the aluminum valve holder on the front of the face piece and, to the other end, to the neck at the top of the filter container. The E Mk VI container, ordered into production in 1940, offered improved protection against arsine gases and was identical to the Mk IV but for its color. It remained in service until the entire gas mask assembly was replaced by the Light Assault Respirator in 1943. The brick red painted metal canister is 14cm tall and 12cm at the widest point of its rounded sides. The top of the canister is ink stamped with a "C-broad arrow", as well as embossed "19/1/42 0 SBT 153" while the base is stamped "G.S.W", No. 4A, AC/4 and E/V1". Three horizontal ribs run along the top half of the body of the canister, and horizontal and vertical ribs are to its lower half. Along one lower side are two horizontal slots where the air is taken in.