Upgrade your defenses and boost allergen protection. AllergenBlock* defense layer neutralizes over 90% of the allergen properties such as sneeze-inducing dust, pollen and pet dander that can trigger discomfort. Blue Pure 211i Max Series AllergenBlock Blueair filter is designed for optimal performance. Compatible with Blue Pure 211i Max air purifier. *AllergenBlock refers to inanimate allergens pollen, dust and pet dander. Based on ELISA deactivation testing of Pollen (Cry J1), Pet Dander (Fel d1, Can F1), Dust Mite Matter (Der f1) on the filter media in 60 minutes.