... With double in-turned lip seal2) Universal size3.1 .First class: chemical agent: Hydrocyanic acid, cyanogens chloride, arsine, phosgene, ... carbon disulfide, carbon tetrachloride, nitroalkanes, and etc;3.2.Second class: biological bacteria: The plague, cholera, anthrax, etc;3.3Third ... class: radioactive substance: Radioactive dust. 3.Packing: per unit ...