The water panel evaporator pad is the vital component of your furnace humidifier which supplies clean and moist air promoting both a healthy and comfortable environment to live in. For best performance change at least once per season depending on water conditions and frequency of use. High output water efficient ceramic-coated metal water pad fits aprilaire 350, 360, 560, 560A, 568, 600, 700, 760, 760A and 768 (35). Fits honeywell HE200A, HE250A, HE260 A/B, HE265A/B, ME360, HE360A/B and HE365A. Fits Lennox WB2-17, WB2-17A, WP2-18 and WP2-18A20. Dimensions: 1-1/2" x 10" x 13".