The fabric allows water to pass into the drain core while restricting the movement of soil particles which might clog the core. The core allows the water to flow to designated drainage exits. Enka® 3D Drain 20 is designed for vertical applications. Enka® 3D Drain 20 with 1/4” height can move more water per foot width than a layer of stone which is 1 ft. wide and 120 in. high.