Keep your pond water at its cleanest using the Savio Living Ponds Filter Top Polishing Mat. This mat fits inside all Savio Living Pond Filters above the biological media. The mat features a permeable design allowing water to pass through but trapping any solid debris. Place this mat above the biological media in the filter container to provide clean nourishing water to your pond and keep it fresh all season long. Construction: fibrous filter media. Dimensions: 19" L x 19" W x 1" H.