Breathe easy with the Bionaire Colorcheck^® Whole House Smart Humidifier Filter. The Cabron X Layer and Antimicrobial Treated Layer work to help prevent the growth of bacteria that can cause stains and odours of adversely affect performance. The exclusive Colorcheck^® Filter Change Indicator turns from purple to red when the filter needs replacing. The filters are affixed to the humidifier interior door panel for easy convenient replacement.