1. - The upgraded FLT4825 HEPA filter B replacement is designed to be compatible with AC4825, AC4300, AC4800, AC4900, AC4850, AP2200CA and Black+Decker BXAP148 air purifiers. Replaceable FLT4825PT HEPA filter B 2. - Different from the ordinary FLT4825 filter, we have upgraded the product for the second time. Adopting a 2-stage filtration system (① H13-level true HEPA filter ② ARC formula activated carbon filter). The upgraded filter B will bring you high-capacity filtration performance more efficiently and conveniently, and thoroughly solve the problem of more substances in the air 3. - Use the upgraded FLT4825 replacement filter to enjoy fresh air all year round and relieve the uncomfortable symptoms caused by air problems. 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 fresh4.- Our upgraded FLT4825 replacement filter stands out from the competition with its unparalleled multi-layer filtration technology, which has been rigorously scientifically tested in independent laboratories, skillfully combining HEPA 13 / MERV 17 non-woven fabric with activated carbon through careful engineering. Using replacement filters guarantees the performance of your air purifier and ensures that the product you purchase is worth your investment5.- - Package contains 4 x 2-in-1 True HEPA filters and 8 x Activated Carbon filters. Filter dimensions: Height: 15.75 x Length: 4.53 x Width: 1.18 inches. We recommend that you replace the FLT4825 filter every 6-8 months for optimal performance. Easy to replace and handle, no tools required. Simply remove from the machine unit and replace when needed.