SCALE CONTROL INSERT 400 APRILAIRE (6)

Aprilaire® Replacement Scale Control Insert, For Use With: Model 400 Humidifier, Plastic, Black, 14 in H x 10-1/4 in W x 5 in Thk 

The Aprilaire Scale Control Insert 4403 is the U-shaped component which encases the Water Panel. It directs any built-up mineral deposits back into the water panel, and it prevents water from leaving the wet-pack section and entering another portion of the humidifier. Used with the water panel number 45, and the distribution tray number 4407.