Honeywell 50000293-003 Post Filter Sold in a pack of two. Boosts efficiency by 8-10%! Captures up to 98% of particles between 3 and 10 microns in size - cat dander, pollen and dust. Enhances air cleaners filtration efficiency in capturing bacteria, smoke, particles, mold spores and other fungi. Antimicrobial coating protects against bacteria and fungal growth on the filter.