Filtrete 18"x24"x1" Gray Basic Dust & Lint Pleated Furnace Air Filter. Electrostatically charged, it effectively attracts and captures large airborne allergens like pollen, household dust, and lint. Designed for high velocity heating/cooling systems, this filter outperforms ordinary fiberglass and washable 1" filters. For residential use only, it has an MPR rating of 300 and lasts up to 3 months.