Compatible Models: Our humidifier filters are designed to work with Honeywell models HAC-504, HAC-504AW, HAC-504V1, HCM-350, HCM-350B, HCM-300, HCM-450B-CST, HCM-500, HCM-550, and more. High-Quality Construction: Made from robust reinforced mesh paper, our filters feature hot glue strips and a dense structure to enhance filtration efficiency and reduce sagging when wet. This design ensures optimal moisture return to the air. Exceptional Performance: Experience relief from dry air discomfort with our replacement filters. The absorbent mesh paper effectively filters impurities from the water, preventing white dust accumulation in your indoor air and maintaining peak humidifier performance. Cost-Effective Solution: Each package includes four standard white humidifier filters for Honeywell HAC-504. Filter dimensions: 7.0 in (H) x 5.3 in (W) x 4.8 in (D). For best results, fill your humidifier tank with distilled water to prevent filter degradation from hard water. Recommended Maintenance: We advise replacing your compatible Honeywell HAC-504 filter every 2-3 months, depending on usage and environmental conditions, to ensure continued high performance. Trustworthy Shopping Experience: We are committed to providing a seamless shopping experience for our customers. We stand behind our products and prioritize customer satisfaction. If you encounter any quality issues, please reach out to our customer service team, and we will work to resolve your concerns promptly.