Replacement Activated Carbon Filter for Leitz TruSens Z-2000 / Z-2500 Medium Pet Filter Drum, 1 Piece. This filter with 2 layers of activated carbon pellets provides a protective barrier against unwanted pet odors in your home. This activated carbon layer is specifically designed to remove odors and volatile organic gases (VOCs) and is compatible with the pet HEPA filter drum for the Leitz TruSens Z-2000 / Z-2500 air purifiers (item LEITZ Z-2000EU / item LEITZ 2415138). Notice: To maintain the optimal performance of your air purifier, it is recommended to replace the pet activated carbon filter every 3 months (depending on the duration of use). Package contents: