Holmes HWF100 Humidifier Replacement Filter, Set of 3 3-pack of replacement humidifier filters with reinforced outer layer Traps mineral deposits from water so humidifiers can run more efficiently Treated with Arm & Hammer Baking Soda and Microban Antimicrobial Product Protection Install at the beginning of each season, replacing every 2 to 4 weeks or as [...]Holmes HWF100 Humidifier Replacement Filter, Set of 3 is a post from: Hunter Humidifier Filter