The White Westinghouse M3300 Compatible Humidifier Filter features honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your home and fits models WWHM3300, WWHM3400, WWHM3500, WWHM3640, WWHM3600 and WWHM3650.
It measures approximately 7 3/4" H x 7 1/2" ID x 9 1/2" OD x 1".
For best results, change air filter at least twice per season or more often depending on air quality and use.