Filtrete Products - Filtrete - Allergen Reduction Furnace Filter, 14 x 20, 2/Pack, 2 Packs/Carton - Sold As 1 Carton - Electrostatically charged fibers attract and capture airborne allergens. - Works on pollen, mold spores and dust mite debris. - Also effective against smoke, pet dander, household dust, smog and candle soot. - 1200 MPR (microparticle reduction) rating. - Lasts up to three months. Electrostatically charged fibers attract and capture airborne allergens. Works on pollen, mold spores and dust mite debris. Also effective against smoke, pet dander, household dust, smog and candle soot. 1200 MPR (microparticle reduction) rating. Lasts up to three months.