Genuine MA-18 replacement filters should be used to maintain the effectiveness of the MA-18 air purifier unit. Removes 99.9% of harmful toxins including allergens, odors, VOCs, smoke, pollen, pet dander, dust, smog, contaminants, and more down to 0.1 microns in size. Perfect for clean air in bedrooms, baby nurseries, living rooms, home gyms, kitchens, offices, and more. Maintain your purifier's Lifetime Warranty by replacing the MA-18 filter every 4 months or after 2,000 hours of use, whichever comes first.