Check out this convenient annual humidifier maintenance kit from Aprilaire! Everything you need to maintain your Aprilaire humidifier is included in this OEM Aprilaire Humidifier Maintenance Kit, Aprilaire part number 4792. The Aprilaire 4792 Maintenance Kit is designed specifically for your Aprilaire 500, 500A or 500M Humidifier and includes: Water Panel Scale Control Insert Drain Spud Orifice Water Feed Tube In-Line Strainer Distribution Tray Purchase this handy Aprilaire 4785 maintenance kit and say goodbye to the hassle of keeping track of when to clean or replace the various components in your Aprilaire humidifier. Simply buy this kit and you can return your Aprilaire humidifier back to factory "new" condition each year!