This Lennox Water Panel features honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your home and fits humidifier model WB2-17, WB217, WP2-18 and WP218. It measures approximately 10″ x 13 1/4″ x 1 1/2″ and for optimum performance, replace panel twice a season or more often in hard water areas.