[Replacement recommendation]In order to maintain the excellent performance of your blue pure 411 air purifier, blue pure 411+ air purifier or mini air purifier, we recommend changing the filter every 6 months or so when it is used 24 hours a day. [True H13 HEPA Filter]The filtration efficiency for 0.1 micrometre particles is as high as 99.97%, such as pollen, pet dander. [Superior Performance]Has excellent noise control, workmanship, higher capacity and longer filter without sacrificing blue pure 411 air purifier performance.The delivery rate(CADR) after replacement is no different from the filter. [Unlike Other Activated Carbon Air Filters] It has the characteristics of developed pore structure, large specific area, strong adsorption capacity and high strength. Easily remove household odors, such as smoke, chemicals, and volatile organic compounds(VOCs). [Matching model& Attention]Suitable for blue pure 411 air purifier, blue pure 411+ air purifier and Mini air purifiers.Attention: Please check your air purifier when you buy it.