The SR 299-2 is a combined filter consisting of a Class 1 gas filter and Class 3 particle filter. The filter is designed for use in Sundström full face masks and half masks. The filter is of type ABEK1-Hg-P3 R and provides protection against the following types of gases, vapours and particles: Type A protects against organic gases and vapours, such as solvents, with boiling points > +65 °C. Type B protects against inorganic gases and vapours, such as chlorine, hydrogen sulphide and hydrogen cyanide. Type E protects against acidic gases and vapours, such as sulphur dioxide and hydrogen fluoride. Type K protects against ammonia and certain amines, such as ethylene diamine. Type Hg protects against mercury vapour. Warning. Maximum use time (Hg) 50 hours. Type P3 R* protects against all types of particulate pollutants, e.g. dust, mist and smoke. *R (Re-useable): The filter is intended to be used for more than a single shift.