The AprilAire 4335 Feed Tube with Sleeve is the water feed tube inside the humidifier, which connects the solenoid valve and then to the water distribution tray at the top of the unit. For use with Models 400, 400A, 400M, 500, 500A, 500M, 600, 600A and 600M. Includes #4004 In-Line Strainer and #4231 Yellow Orifice. Also includes compression sleeve and compression nut. Also see maintenance kits #4788 (400 Series), #4792 (500 Series), and #4839 (600 series).