Aprilaire® Replacement Scale Control Insert, For Use With: Model 500 Humidifier, Plastic, Black, 10-7/8 in H x 10-1/2 in W x 2-5/8 in Thk
The Aprilaire Scale Control Insert 4640 is the U-shaped component which encases the Water Panel Evaporator. Used with water panel number 10 and water distribution tray part number 4331. For Models 500, 500A and 500M.