The Whirlpool APR25530L Whispure 255 Air Purifier, ideal for rooms up to 307 square feet (17' x 18'), features a True HEPA filter for the ultimate level of filtration against airborne allergens. A carbon pre-filter captures common household odors, and the electronic filter indicator lets you know exactly when to replace the filters. 99.97% True HEPA Filter! Replaceable True HEPA Filter 1183250 (included, replace once per year) captures up to 99.97% of airborne particles and allergens as small as 0.3 microns from the air that passes through the filter. Also helps to reduce airborne germs such as mold spores, bacteria, and fungi. Odor Reducing Prefilter! Replaceable Carbon Pre-Filter 8171433K (included, replace every 3 months for maximum odor reducing performance) captures large particles such as dust, lint and hair. The activated carbon prefilter also deodorizes the air and reduces common household odors.