The FilterQueen Defender Medi-Filter includes: (1) Medi-Filter: The Medi-Filter provides three times better-than-HEPA filtration to reduce pollutants such as dust, dust mites, pollen and mold spores. Note: For the best Indoor Air Quality experience, purchase the Enviropure Charcoal Filter Wrap in addition to the Medi-Filter. How often to change your filters: Medi-Filter: Change once every year. For best results, change every 6 months for homes with pets or smokers. To order filters call (877) 746-6680 or place your order below.