Filter-Monster branded replacement filter compatible withAustin Air Allergy Machine FR405 Air Purifier filter. Fits Austin Air models HM405, HM410, HM402, HM400, HM450. 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 Allergy Machine FR405 Air Purifier filter. Package contains one (1) filter and two (2) carbon pre-filters. Engineered to fit Austin Air Allergy Machine (HM405) Air Purifier. Also fits Austin Air models HM410, HM402, HM400, HM450.