1. - The FLT4825 HEPA Filter B Replacement Set is designed to be compatible with AC4825, AC4300, AC4800, AC4900, AC4850, AP2200CA and Black+Decker BXAP148 air purifiers. For use as a replacement for the FLT4825 HEPA Filter B. NOTE: This product is not an OEM product. Any brand name or model designation used on this product is used solely to demonstrate compatibility. 2. - Our upgraded FLT4825 replacement filter stands out from the competition with its unmatched multi-layer filtration technology that has been rigorously scientifically tested at independent laboratories and ingeniously combines HEPA 13 / MERV 17 non-woven fabric with activated carbon through careful engineering. Using a replacement filter guarantees the performance of your air purifier, ensuring that your purchase is worth the money 3. - Enjoy fresh air all year round and relieve uncomfortable symptoms caused by air problems with the FLT4825 replacement filter. The H13 True HEPA filter works with the high-efficiency activated carbon filter to remove 99.97% of airborne substances as small as 0.03 microns, and effectively decomposes unpleasant household odors and wildfire gases, keeping the air in your living environment fresh 4.- - Package contains 4 x H13 True HEPA filters and 8 x activated carbon filters. HEPA filter dimensions: Height: 15-7/10' x Length: 4-1/2' x Width: 1-3/10', Carbon filter dimensions: Height: 15-7/10' x Length: 4-1/2' x Width: 1/5'. For optimal performance, we recommend that you replace the HEPA filter every 6-8 months and the pre-filter every 2-3 months. Easy replacement, no tools required. Simply remove from the machine and replace when needed.