FilterBuy HWF72 / HWF75 Replacement Humidifier Filter. Fits Holmes humidifier Models HM850, HM3300, HM3400, HM3500, HM3501, HM3600, HM3640, HM3641, HM3650, HM7600, HF221 and HSL5000 Premium aftermarket replacement, designed by AFB in the USA. AirFilterBuy: Breathe Better! This humidifier filter is designed to prevent growth and migration of mold, fungus, algae, and bacteria Designed to fit Holmes humidifier models HM850, HM3300, HM3400, HM3500, HM3501, HM3600, HM3607, HM3608, HM3640, HM3641, HM3650, HM3655, HM7600, HF221, and HSL5000. HWF72/HWF75 Holmes Replacement Humidifier Wick Filter. Aftermarket replacement filter manufactured by AFB