Filtrete 12"x20"x1" Red Micro Allergen Defense Pleated Furnace Air Filter. It effectively captures large allergens like mold spores and pet dander, while its electrostatic charge traps microscopic allergens like dust, smoke, and smog. This filter also captures bacteria and particles that can carry viruses, meeting the guidelines of the American Lung Association Health House Program. With a MPR rating of 1000, it lasts up to 3 months, providing you with clean and healthy air.