4640 SCALE INSERT 500A/5 00M

The AprilAire 4640 Scale Control Insert is the component which encases the Water Panel. Use with Water Panel Number 10 and Water Distribution Tray number 4331 — both sold separately. This part is for use in Humidifier Models 500, 500A, and 500M. All parts mentioned above are included in the number 4792 Maintenance Kit.