Maintain healthy indoor air quality with this three-pack of replacement humidifier filters. They install easily and feature a reinforced outer layer for extra durability. To help humidifiers run more efficiently, the filters trap mineral deposits from the water, plus they come treated with Arm & Hammer Baking Soda and Microban Antimicrobial Product Protection for enhanced performance. A new humidifier filter should be installed at the beginning of each season and replaced every two to four weeks depending on usage. Bionaire humidifier models BCM4600, BCM645, BCM646, BMC5520, BCM5520RC, BCM5521, BCM4600, BCM5520RCU, BCM6000, BCM6010, BCM6010RC, BCM6610RC, BCM7203, BCM7203RC, BCM7204, BCM7205, BCM7207, BCM7305, BCM7305RCB, BCM-7305RC, BCM7306, and BCM7307. Holmes humidifier models HM729, HM729G, HM630, HM7204, HM7305/RC, HM7306, HM6000, HM6000RC, HM6600, HM6005HD, and HM4600/HD. The three-pack of humidifier filters measures approximately 5-3/5 by 4 by 7-4/5 inches.