About this item Compatibility : This 311i Max replacement filter is fully compatible with BLUEAIR HEPASilent Air Cleaner, Blue Pure F3MAX, and Model Blue Pure 311i Max. Attention Please :This Filter is ONLY compatible with BLUEAIR HEPASilent Air Cleaner, Blue Pure F3MAX, and Model Blue Pure 311i Max. Not for 211 and 211 Auto, 411i max, 411a max,511, 311, 311i MAX121, or other models, Please check the model number before placing the order High Efficient Filltering The HEPA filt-er Clean at least 99.97% of tiny airborne particles like smoke down to 0.1 microns, and cleans pet dander, and dust, The activated carbon filt-er cleans up light households from smoking, pets, and cooking fume Performance Peak For your machine performance peak, based on actual usage the filter should be replaced every 6 months, it’s easy to install, and no tools are required. We Treasure Our Customers : If you have any questions about our product, please feel free to contact us, and we’ll solve them within 24 hours. Filter made of FSC-Certified paper