AprilAire makes maintenance easier than ever with the Humidifier Filter / Water Panel Assembly Replacement Kit for AprilAire Whole-House Humidifier Models 400, 400A, and 400M. This all-in-one replacement kit (2-pack) is fully assembled for fast, simple maintenance that keeps your humidifier running like new. No need to remove scale buildup or manually clean any parts of the water panel assembly, just remove and discard the old one and slide in the replacement kit to refresh the performance of your AprilAire Whole-House Humidifier. A properly maintained water panel helps deliver balanced humidity levels throughout your home, creating an environment where dust mites, viruses, and other asthma and allergy triggers are less likely to thrive. You'll find detailed instructions on the box with helpful visuals and step-by-step guidance to make the process a breeze. AprilAire recommends replacing the water panel assembly twice annually. Note: when changing out the old water panel assembly, retain the floats and float cover to use with the replacement assembly.