Aprilaire Humidifier Maintenance Kit for 550 series
This is a Maintenance kit for Aprilaire Humidifier Models 550, 550A, and 558. This kit contains the following: 1 #10 pad, 1 #4226 Feed Tube, 1 #4321 Yellow Orifice, 1 #4217 Scale Control, 1 #4004 Strainer,1 #4184 Nozzle, 1 #4218 Distribution Tray, and 1 #4223 Drain Spud.