Honeywell HAC-504 Series Humidifier Replacement, Filter A - 2 Filters (Updated Version) Bundled with.

2 FILTERS, BUY MORE, SAVE MORE: Stock up so you shouldn't run out! Blue pre-filter layer helps capture large airborne particles from the air that passes through the filter. Protec treated antimicrobial filter inhibits up to 99% of mold growth. Antimicrobial treatment helps prevent the growth and migration of mold, fungus and bacteria on the filter. Wicking filter captures minerals and pollutants from Fluid and helps prevent white dust.