Precise Compatibility -- Our 211i Max replacement filter are fully compatible with Blueair Blue Pure 211i Max Air Puri-fier, for part # F2MAX. Not compatible with 211+ and 211+ Auto. Please check the models of your machines. 2 in 1 Filtration -- H13 true he-pa absorbs pet dander and dust, attaching 99.97% of particles down to 0.1 microns in size. Activated Carbon Filter absorbs cooking smells and pet odors. Release clean air for your home!