Fellowes Carbon Filters for AeraMax Air Purifiers - 4 Pack (9324201) Carbon Filter removes odors and captures large airborne particulates Compatible with Fellowes AeraMax 300 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 3 months to keep your air purifier running at peak performance A filter change indicator on your Fellowes AeraMax 300 Air Purifier conveniently notifies you when it's time to replace your carbon 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.