This Honeywell Replacement Wicking Filter "C" is for use with Honeywell HEV320 series & HCM-890 series humidifiers. It helps remove minerals & pollutants from the water & reduce white dust. The Protec Antimicrobial Treated Filter helps prevent the growth & migration of mold, algae & bacteria on the filter and it inhibits up to 99.99 percent of mold growth on the filter. 1) The Air Wash blue pre-filter layer removes large particles from the air and provides additional structural support, 2) The optimized design maximizes moisture output. 3) Designed exclusively to fit Honeywell humidifiers, 4) Includes one wicking filter.