1.Compatibility: Our flt4825 filter replacements are compatible with Guardian AC4825, AC4825E, AC4300BPTCA, AC4850PT, AC4900CA Air Purifier. Note: Not Compatible with the AC Series Air Purifier. It's Not FLT Or Filter C 2.6 Extra Pre-Filters: You can extend the life of the HEPA by changing the pre-filter more frequently. Activated carbon pre-filter reduces odors and VOCs from cooking, smoking, pets and more. 3.High-Efficiency Filtration: The H13 true HEPA filter captures 99.97% of airborne particles as small as 0.3 microns. 4.Value Pack: The package includes 3 true HEPA filters and 9 pre-filters for up to 18 months of use. Save money and hassle by buying in bulk and enjoy fresh air every moment. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.