The Leitz TruSens Replacement 3-In-1 HEPA Drum Filter has been engineered to collect ultra-fine airborne particles including bacteria, viruses, dust, allergens, pet dander, volatile organic components (VOC?s) and odorous gases. The 360 degree filtration draws in air from all directions, collecting pollutants from around the room that may affect allergies and other symptoms. A washable prefilter offers the first level of defence against dust and pet hair. Hand wash with mild soap as needed. The carbon prefilter captures odours and certain gases. The Change indicator light is displayed on the air purifier when filters need to be replaced. Compatible with Leitz TruSens Z-3000 / Z-3500 Large Air Purifier.