Grid features 100 percent polypropylene cloth, uses a higher denier and different weave pattern, which allows for better control of the fabrics permeability. Polypropylene is also rot and mildew resistant and has excellent resistance to alkalis and acids. Filbur grids had better dirt holding characteristics and lower pressure drop than the competition. This grid is designed to use with Universal pro kit 48-square feet swimming pool DE filter. Measures 24-inch length. Replaces Unicel DE grid filter model FS-2004.