To protect the science teacher during brief periods of exposure to acid fumes, organic solvent vapor, and dust-—these are NIOSH-approved respirators. The face mask is of pliable plastic. Can be worn with glasses or chemical splash goggles. This is not a life-sustaining device and is meant only for use in an environment where the oxygen level is still quite good. Replacement cartridges—filters for acid, organic vapor, and dust protection—are available separately in packages of two filters.