Comfort-Aire humidifier systems require the use of a cut-to-fit style foam replacement filter pad. This material comes in an approximate size of 6″ x 65″ x 3/8″ and can be trimmed to the desired size you need to replace your humidifier filter. Available model numbers include HCF10, HCF12, HCF13, HCF15, and HCF120. These offer high-efficiency foam construction to keep your humidified water clean from impurities and minerals.