The Winix 115115 Replacement Filter A is a complete one-year filter set. The Winix True HEPA Filter captures 99.99% of airborne allergens including pollen, dust, smoke, pet dander, and other ultrafine particles as small as 0.003 microns. The 4-pack Carbon Filters trap large particles, extending the life of the True HEPA Filter and absorbs odor in the environment. Winix Replacement filter A lasts 12 months.