Filtrete 20"x25"x1" Gray Basic Dust & Lint Pleated Furnace Air Filter with MPR 300. It is electrostatically charged to attract and capture large airborne allergens like pollen, household dust, and lint. It is ideal for high velocity heating/cooling systems and performs better than ordinary fiberglass and washable 1" filters. It lasts up to 3 months and is for residential use only.