... # filter 5.at economic price Product Name: half face chemical gas respirator with single filterModel No.: FD-1Product DetailsPacking & DeliveryMaterialframe: ... 3# or 7# filter3# (HX-3)Used to prevent organic gas and steam damage to human body, such as benzene, chlorine ... bromide, chloromethane, nitroalkane.7# (HX-7)Used to prevent acid gas and steam damage to human body, such as carbon dioxide ...