Maintaining proper humidity levels is integral to maintaining Healthy Air. This genuine AprilAire replacement water panel humidifier filter is made with heavy-duty paper reinforced with two layers of aluminum and coated with an anti-microbial agent to prevent the growth of biologicals. The panel absorbs water and maintains the proper level of hydration to support the evaporation process. Water is vaporized as air warmed by the furnace passes over the water panel. The humidified air is carried through the house through the air ducts. AprilAire has been there since the beginning by introducing the first whole-home humidifier in 1954. Since then, we've continued to focus on quality design, engineering, and manufacturing to deliver Healthy Humidity to every home. Healthy Humidity reduces the incidence and risk of respiratory infections from airborne viruses. It also helps remedy your dry skin, chronic sore throat, frequent nosebleeds, and static shock. Additionally, proper humidity levels protect your home's wood furnishings from cracking or splitting while lowering your energy bill. Keep your AprilAire Humidifier running at peak performance by replacing your water panel twice during the heating season. The Model #45 Water Panel dimensions are 9-7/8" W x 12-7/8" H x 1.75" D and illustrated instructions help you change your water panel quickly and efficiently.