Filtrete 14"x24"x1" Gray Basic Dust & Lint Pleated Furnace Air Filter. Electrostatically charged to attract and capture large airborne allergens like pollen, household dust, and lint. Ideal for high velocity heating/cooling systems. Performs better than ordinary fiberglass and washable 1" filters. For residential use only. MPR rating of 300. Lasts up to 3 months.