This Honeywell Humidifier Filter Replacement, Wicking Filter “A” helps capture minerals in the water in your humidifier, and also helps reduce white dust. It uses a patented design that helps inhibit 99.99% of growth and migration of particles on the filter. A blue pre-filter layer helps capture large particles. The Honeywell “A” wicking filters work with evaporative Honeywell humidifiers in the HCM-350, HEV355, HCM-710 & HCM-315/HEV312 model series. Using humidifiers helps to ensure proper humidity levels in your home. Indoor humidity levels between 40-60 percentage can help relieve cough and congestion, keep throat and nasal passages hydrated and more. They can be especially helpful during cold and flu season, when it's difficult to sleep with cough and congestion. A humidifier or vaporizer can provide temporary relief by adding necessary moisture to the air. For best performance, use only these Genuine Honeywell humidifier filters. Compatible humidifier filter replacements are not certified to offer the same performance or efficiency.