Carbon Filters for AeraMax Pet PT65 Air Purifier, 2-Pack (9406402) Helps reduce odors and allergens from caged pets, litter boxes and pet dander Compatible with Fellowes AeraMax Pet PT65 Air Purifier. This items packaging will indicate what is inside and cannot be hidden. With normal usage, it is recommended that you change your filter every 12 months to keep your air purifier running at peak performance A filter change indicator on your Fellowes AeraMax Pet PT65 Air Purifier conveniently notifies you when it's time to replace your HEPA filter To ensure optimal performance, only genuine Fellowes filters shipped and sold by Amazon.com should be used. Filters purchased from third party sellers may not be authentic and therefore can cause issues and void product warranties.