The genuine AprilAire 10 Replacement Water Panel is a key component to maintaining Healthy Humidity. It features a porous ceramic-type coating that 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 humidifier filter. The humidified air is carried through the house via the air ducts. Keep the AprilAire Humidifier running at peak performance by replacing your water panel (9-1/2 in. W x 9-3/4 in. H x 1-3/4 in. D) annually. The genuine AprilAire 10 Water Panel is designed and the leader in Indoor Air Quality solutions for the home since 1954.