Package includes: 2 True HEPA Filters + 4 Carbon Booster Pre-Filters. Designed to fit aer1 ready air purifiers，Replaces A Filter，D Filter，K Filter. Compare to Holmes aer1 hepa-type total air filter HAPF30AT. Compatible with Bionaire UNITS：BAP260，BAP815，BAP825，BAP9200，BAP9700，BAP520. Compatible with Holmes UNITS：CAP531-U，CAP529-U，HAP240，HAP242，HAP412，HAP422，HAP424，HAP706，HAP716，HAP9240，HAP9242，HAP9412，HAP9414，HAP9422，HAP9424. CARBON BOOSTER PRE-FILTER：Absorbs household odor from pets, cooking and smoking. And traps larger air contaminants like pet hair，dust balls，and lint. TRUE HEPA FILTER WITH H13 GRADE：Captures 99. 97% of pollutants as small as 0. 3 μm such as dust，pet dander，and pollen. True HEPA Filter keep your Holmes air purifier working at its full capacity.