Filter Pad Holding Frame, Actual Height 17 1/2 in, Actual Width 24 1/2 in, Actual Depth 3/4 in, Frame or Header Material Galvanized Steel, For Use With Filter Pad, Nominal Filter Size 18x25x1, Nominal Height 18 in, Nominal Width 25 in, Nominal Depth 1 in, Filter Pad Holding Frame.