Approved vapor protection against 50 ppm hydrogen chloride, 50 ppm sulfur dioxide, 10 ppm chlorine, and 1000 ppm organic vapors having good warning properties. Hydrogen Chloride is one of the fumes emitted from salt kilns. However, because of the variable emissions from a salt kiln, the appropriateness of using this mask during the salt firing process must be carefully considered. This cartridge is also useful for application and firing of metallic lusters. These Cartridges fit the New Series (black) DC masks. Sold in Pairs only: one Pair required per mask.