18x25x1 Filtrete Filter, Case of 4

18" x 25" x 1", Purple, Ultra Allergen Filtrete Filter, 3 Month Filter Is 90% Effective At Capturing Large Allergens Like Mold Spores & Pet Dander, Electrostatically Charged, Captures Microscopic Allergens Like Dust, Smoke & Smog, Captures Bacteria & Particles That Can Carry Viruses, Meets The Guidelines Of The American Lung Association Health House Program, MPR Rating 1500, Lasts Up To 3 Months.