Fits models 110, 220, 500, 500A, 500M, 550, 550A, and 558. Designed to Fit: Fits Aprilaire humidifiers requiring the #10 filter, models 110, 220, 500, 500A, 500M, 550, 550A, and 558. High Efficiency Filtration: Reduces pollutants from the water used in your humidifier to produce better air quality.
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