The DuPont Pet Filter with True HEPA features a combination filter with 3 levels of filtration formulated specifically to combat pet odors and dander. All-in-one filter system combines a True HEPA filter with an activated carbon filter and a separate washable prefilter. Dupont 360-degree filtration draws in air from all directions, collecting pollutants from around the room. The filter is at the core of purifying your air and replacement is essential for your purifier to perform at its best. Replace every 12 - 15 months and replace the Pet Carbon Filter every 3 - 4 months (depending on usage). Change indicator glows red on your air purifier when the filter needs to be replaced. Compatible with all TruSens Air Purifiers.