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