12" x 20" x 1" Red Micro Allergen Filtrete Filter, 90% Effective At Capturing Large Allergens Like Mold Spores & Pet Dander, 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 1000, Filter Lasts For 90 Days.