https://us.msasafety.com/Air-Purifying-Respirators-%28APR%29/Elastomeric-Full-Face-Masks/CBRN-and-Riot-Control-Gas-Masks/p/000050001700001500

• The Gas Mask must be used with appropriate canister(s) to provide respiratory protection.
• When properly used, the gas mask provides protection against specific contaminates.
• The gas mask is NIOSH approved for CS, Chlorobenzylidene Malononitrile, CN, Chloroacetophenone and all particulate aerosols including oil-based aerosols as listed on the canister label.
• During inhalation, air is drawn through the canister removing or neutralizing the contaminants.
• The inhalation valves open and the exhalation valve remains closed to prevent contaminated air from entering the facepiece.
• During exhalation, the exhalation valves open and the inhalation valve(s) close to prevent exhaled air from passing back through the canister.
• The exhalation valve permits exhaled air to exit the gas mask.