Pleatco PFS1836 Universal 36 Sq. Ft. DE Filter Grid Set Fibrillated fabric has 1008 (42x42) cross-over-points vs. inferior fabrics with 760 (38x20) cross-over-points for more consistent flow and fabric strength Premium frame incorporates a center tube which creates a duct to funnel water from the outer most edges of the grid into the center and through the entire frame. High quality thread to prevent premature grid failure. Replaces Unicel FS-2003 or Filbur FC-9530 The highest quality raw materials and most advanced methods of construction are used to make these high quality replacement DE grids.