COMPATIBLE MODELS Our standard white humidifier filters are compatible with Honeywell HAC-504, HAC-504AW, HAC-504V1, HCM-350, HCM350, HCM350W, HCM-350B, HCM350B, HCM-350W, HCM-350B-CST, HCM-300, HCM-300T, HCM300T, HCM-305T, HCM310T, HCM-315T, HCM305BCST, HCM-450B-CST, HCM450BCST, HCM-500, HCM-530, HCM530, HCM-535, HCM353, HCM-535-20, HCM53520, HCM-540, HCM550, HCM-550-19, HCM55019, HCM-551, HCM-560, HCM560, HCM-600, HCM-630, HCM630, HCM-631, HCM631 humidifiers. Replacement For Honeywell Filter A. STANDARD WHITE FILTER DESIGN Made of high-quality rigid reinforced mesh paper with hot glue strips and dense construction to improve the filter structure when wet and reduce sagging. The design provides higher efficiency, lower pressure, improved quality, and the largest surface area to help return moisture to the air as expected. EXCELLENT PERFORMANCE Provides moist air in winter to ease discomfort caused by dry air. The absorbent mesh paper works with the humidifier to filter impurities in water, helping prevent white powder from entering indoor air and depositing on surfaces, while keeping the humidifier operating at peak performance. COST-EFFECTIVE PACKAGE Includes 4 x Standard White Humidifier Filter Replacement for Honeywell HAC-504. Filter dimensions: H 7.0 x L 5.3 x W 4.8 inches. For best results, fill the humidifier tank with distilled water. Hard water can degrade filters and cause premature yellowing. Replace the compatible Honeywell HAC-504 filter every 2-3 months, depending on usage and environment. USE SCENARIOS - Bedroom or living room during dry winter nights to maintain comfortable humidity levels. - Baby nursery or care environment to reduce irritation from dry air. - Office, study, or small room settings where consistent, clean humidity support is needed.