... acid, cyanogens chloride, arsine, phosgene, chloropicrin, bromomethane, lewisite gas, mustard gas, sarin, vx gas, toxic smoke, and fume, benzene, hydrogen phosphide, chlorine, ... :21kg 4.Usage maintenance and maintain4.1.The selection of gas mask 4.1.1. checking the position between glasses and ... means a right selection. 4.2.The procedure of wearing gas mask 4.2.1. adjusting the position of fillets 4 ...