To prevent unhealthy minerals from collecting in the water droplets and entering the air, includes a powerful ion exchanger;Fits inside the Anton, William, Aquila and Hydra Stadler Form ultrasonic humidifiers;Compatible with most ultrasonic humidifiers with standard tank covers;Depending on the water's hardness, these filters can last for up to 3 months;By removing minerals from the humidifier reservoirs, it prevents the white dust ultrasonic humidifiers create