Walton USA12-UWN Humidifier Water Panel Fits Walton furnace humidifier models 600&#44; 620&#44; PBR620&#44; PFS-640&#44; 660&#44; and PFR660. Measures approximately 11 1&#47;2 x 14 3&#47;4 x 1 5&#47;8 in. Honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your Black paint mark indicates top of panel. For optimum performance&#44; replace panel once every 6 months or more often in hard water areas.