4PK Replacement Filter D fits Holmes, Sunbeam, Honeywell, Westinghouse, Bionaire W & BCM Series Humidifiers # HWF75 SF221 SCM3501 HM3500 HM3600 HC14 HCM6012i W2 W9 W12 BCM3656 BCM5521 WWHM3600 + More Manufactured to fit Holmes, Sunbeam, Bionaire, and White Westinghouse Humidifiers requiring Filter "D Compatible with Honeywell HCM-6009, Sunbeam SCM3609, Sunbeam SCM3755C, Holmes HM3500, 3600, 3640, 3656, Honeywell HC-14, Holmes HWF75, Sunbeam SCM3501, Holmes 3500, Holmes HM3655, Holmes HM3650, HM7600, Sunbeam SCM3609P, Sunbeam SCM3657, Holmes 3501, Sunbeam SF221, Holmes HWF-75, HWF75P, HWF75CS, HWF75PDQ-U, Honeywell HCM-6011, Honeywell HCM-6012i, Honeywell HCM-6013i, Holmes 3650, Holmes 3607, Sunbeam SCM3502, Holmes "D" Also replaces Bionaire W2, W6, W7, W9, W12, W14, W15, W25, BCM600, BCM700, BCM2200, BCM3600, BCM3656, BCM3855, BCM3955, BCM4600, BCM5520, BCM5521, BCM5555, BCM6000 BCM7203, BCM7305, BCM7306, BCM7510, White Westinghouse WWHM3300, WWHM3600, and many more! Traps water impurities and is designed to prevent growth and migration of mold, fungus, algae, and bacteria. For best results, change air filter at least once per season or more often depending on air quality and use.