Flanders PrecisionAire 85756.011212 NaturalAire Micro Particle Red Pleat Air Filter (4 Pack), 12 x 12 x 1" Lasts up to 90 days Electrostatically charged Provides economic savings Provides allergy relief Effective protection against dust and lint, dust mite debris, pollen, pet dander, mold, bacteria, virus carriers, smoke and smog