This Air O Swiss humidifier demineralization cartridge is brand new and has never been used. It is compatible with a wide range of Air O Swiss humidifiers and helps to prevent mineral buildup in the unit, ensuring clean and efficient operation. Made from high-quality plastic, this cartridge is designed to last and provide reliable performance for years to come. With a tank capacity of 7.5 L and an ultrasonic humidification method, this cartridge is perfect for use in any small to medium-sized room, such as bedrooms, bathrooms, closets, hallways, and dining rooms.