The 79830-999 is a replacement filter for Honeywell TrueHEPA air purifiers that helps to remove airborne allergens, particles, and odors from the air. This filter is designed to capture 99.97% of particles as small as 0.3 microns, including pollen, dust, mold spores, smoke, pet dander, and other microscopic particles that can cause allergies and other respiratory issues. The filter also contains an activated carbon pre-filter to capture larger particles and help reduce odors from pets, cooking, and other sources.