AeraMax PRO AM3-4 10mm Carbon Filter with Pre-filter, Pack of 4Commercial grade Activated Carbon Filter absorbs a wide range of volatile organic compounds (VOCs) and odours. Includes separate Pre filter to capture larger particulate to help extend life of subsequent filters. Compatible with Fellowes AeraMax PRO AM3, AM3S, AM4 and AM4S Air Purifiers. Replace the Carbon Filter approximately every 6 months, depending on usage conditions, in order to ensure that the Air Purifier remains effective. Pack of 4 Carbon