Fits Honeywell humidifiers requiring HAC-504AW filter, models HCM-530, HCM-535-20, HCM-540, HCM-550, HCM-550-19, HCM-551, HCM-632,
HCM-632TG, HCM-640BW, HCM-1000C, HCM-1010, HCM-2000C, HCM-2001, HCM-2002, HCM-2020, HCM-2050, HCM-2051, HCM-2052, HCM-300T,
HCM-305T, HCM-305T-CST, HCM-300T, HCM-315T, HCM-350, HCM-350B, HCM-535, HCM-560, HCM-630, HCM-631, HCM-635, HCM-645, HCM-646,
HCM-650, HCM-710, HCM-1000, HCM-2000, HEV-312, HEV-355