Austin Air FR250B Healthmate Junior Plus Replacement Filter, WhiteSTAGE 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 Over 269 cubic inches of Activated Carbon, Potassium Iodide Impregnated Carbon and Zeolite. Removes Volatile Organic Compounds (VOCs), formaldehyde, benzenes, chemicals, gases and odors. STAGE 4 30 sq. ft. of True Medical