This “Compatible” filter measures approximately 9 1/2& x 10 x 1 1/2 and Fits Hamilton model 12HF. Honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your home. Water Panels are the heart of your humidifier. It is the component that generates the important humidity to keep you comfortable during the heating season. Black paint mark indicates top of filter. For optimum performance, replace Water Panel once every 6 months or more often in hard water areas.