Model Compatibility: Filter-Monster Replacement with Carbon Filter Set compatible with Coway 400/400S Airmega Max 2 filter. Engineered to fit Coway Airmega 400 and 400S air purifiers. Replacement Time: Depending on air quality environment and usage, it is recommended to replace the filter every 12 months to help ensure the Coway Airmega air purifier is running efficiently. Dimensions: Filter-Monster Replacement with Carbon Filter Set compatible with Coway 400/400S Airmega Max 2 filter. The air filters approximate dimensions are: 14.37" x 11.02" x 1.77”. Included in the package are two (2) replacement filters. Filter-Monster replacement compatible with Coway 400/400S Airmega Max 2 filter. Engineered to fit Coway Airmega 400 and 400S air purifiers. Activated carbon removes harmful VOCs and household odors from cooking, cleaning, smoking and pets. Package contains (2) replacement filters, one for each side of your air purifier.