Aprilaire Yellow Orifice #4231

The Aprilaire Yellow Orifice #4231 is the tiny nylon components which accurately meter the flow of water into your humidifier, allowing a specific amount of water unique to your model.

Compatible Models

• 400, 400A, 400M
• 500, 500A, 500M
• 550, 550A
• 558
• 560, 560A
• 568
• 600, 600A, 600M