Honeywell Humidifier Wick Filter, Single, HAC-504AW
Replacement Filter for Honeywell Natural Cool Moisture Humidifiers.  Fits models: HCM-1000 Series; HCM-2000 Series; HCM-500 Series; ECM-250i, HCM-600 Series and the new HCM-300T and HCM-310T