The Winix 1712-0110-00 Replacement Filter O is a complete one year filter. The True HEPA Filter captures 99.97% of particles and impurities as small as 0.3 microns, including pollen, mold, dust, pet dander and hair, other allergens and cigarette smoke. The Activated Carbon Filter uses an activated carbon coating to reduce large amounts of odor in the environment. The genuine Winix Filter O is compatible with Winix Air Purifier unit A230 and A231