Austin Air FR205A Allergy Machine Junior Replacement Filter, BlackSTAGE 1 Large Particle Pre filter. Removes particles easily seen by the naked eye (e. g. dust, hair and pet dander). STAGE 2 Medium Particle Pre filter. Removes small to medium size particles (e. g. molds, spores and pollen). STAGE 3 30 sq. ft. of True Medical Grade HEPA. Removes 99. 97% of all particles larger than 0. 3 microns and 95% of all particles larger than 0. 1 microns. STAGE 4 Military Grade HEGA Carbon Cloth. HEGA (High Efficiency Gas