The HM2PR is the correct replacement filter for the following models:
The HM2PR is a compatible equivalent of the Air King 300 Humidifier Filter Belt Replacement. This humidifier filter belt helps reduce the water consumption of your humidifier through its large surface area and makes it run more efficiently. With this humidifier filter you will be able to reduce the mineral deposits and impurities from the water while reaching the full potential of your humidifier.
This drum type filter is made out of plastic foam and fits several different brands and models, which makes it a versatile humidifier belt replacement. Be sure to change the filter regularly for optimum performance, especially if you have hard water.