Washable grease Filters are durable multi-use low efficiency filter which are used in kitchen vent hoods, to protect machinery and for fresh-air intake for commercial HVAC systems. The filters come in thicknesses of 1/4 inch, 3/8 inch, 1/2 inch, 1 inch and 2 inches. Filter media is made of layers of expanded aluminum laid in a varying pattern to ensure maximum efficiency. Easy to clean and handle.Can be made in any size. Multiply height times width to obtain face area