Filter-Monster branded replacement compatible withAustin Air Bedroom Machine FR402 Air Purifier filter. Fits Austin Air models HM402, HM410, HM405, HM400, HM450. Filtration removes up to 99.97% of airborne particles as small as 0.3 microns in size including dust, smoke, pollen, pet hair and dander, mold spores and dust mites. Recommended to change filter once every five (5) years under normal conditions, and more often under harsh air conditions. Package contains (1) filter, two (2) pre-filters. Approximate Dimensions - Diameter: 13.5", Inner Diameter: 7.25", Height: 14.5". Filter-Monster branded replacement filter compatible with Austin Air Bedroom Machin FR402 Air Purifier filter. Package contains one (1) filter and two (2) carbon pre-filters. Engineered to fit Austin Air Healthmate (HM402) Air Purifier. Also fits Austin Air models HM410, HM405, HM400, HM450.