| Genuine Aprilaire 4231 Orifice - Yellow |
 Aprilaire 4231 yellow orifices are the tiny nylon components which, accurately meter the flow of water into your humidifier. They allow a specific amount of water to go into the humidifier, unique to your model humidifier. Used in Models 400, 400A, 400M, 500, 500A, 500M, 550, 550A, 558, 560, 560A, 568, 600, 600A, and 600M. Related Products: Aprilaire 4021 Orifice - Red Aprilaire 4232 Orifice - Blue Aprilaire 400A Humidifier Aprilaire 400M Humidifier Aprilaire 500A Humidifier Aprilaire 500M Humidifier Aprilaire 600A Humidifier Aprilaire 600M Humidifier Aprilaire 800 Steam Humidifier Price: 19.95 |