Replacement Activated Carbon Filter for Leitz TruSens Z-3000 / Z-3500 Large Allergy & Flu Filter Drum, 1 Piece. This activated carbon pellet filter provides a protective barrier against unwanted odors & volatile organic gases (VOCs) that can enter your home. This carbon layer is specifically designed to remove these pollutants from the air, and is compatible with the Allergy & Flu HEPA filter drum for the Leitz TruSens Z-3000 / Z-3500 air purifiers. (Article LEITZ Z-3000EU / Article LEITZ 2415139). Note To keep your air purifier working optimally, it is recommended to replace the Allergy & Flu activated carbon filter every 3 months (depending on the duration of use). Package contents: