Filtrete's 20"x25"x4" Allergen Reduction Filter is designed to effectively capture particles like pollen, mold spores, and dust mite debris, thanks to its electrostatic charge. With an MPR rating of 1550, it ensures efficient filtration and lasts up to 12 months. This filter is suitable for residential use and fits housing units accommodating 4" nominal size filters. Its actual dimensions are 19-3/4"x24-7/16"x4-3/16".