Surround Air MT-8400SF 3-in-1 Spare Filter with True HEPA, Activated Carbon and Pre-Filter 3-in-1 spare filter cartridge includes true HEPA, activated carbon and pre-filter True HEPA air filter for dust & allergens such as pollen, ragweed, mites, mold spores & pet dander Activated carbon filter for odors, chemical vapors and cigarette smoke. Extremely absorbent Cleanable pre-filter for larger particles, prolonging performance & lifespan of other filters