Honeywell HAC504V1 Replacement Filter For Natural Cool Moisture Humidifiers Filter Removes Minerals & Pollutants From Water Filter Has Anti-Microbial Treatment Which Helps Prevent The Growth & Migration Of Mold, Fungus, Algae & Other Bacteria On Filter Fits Honeywell models: HCM-350 Series/ HEV355, HCM-315T Series/ HEV312, HCM-300T, HCM-710, HCM-600 Series Recommended Filter Replacement Interval of 1-2 Months