NDS 13 Plastic Round Grate, 4-Inch, Green Use to drain excess water and direct it to a more water safe area such as a curb or gutter Can be use in large lawn areas, large landscape areas, patios and atriums Can be used with 4" sewer and drain pipe and fittings, 4" corrugated pipe and 4" triple wall pipe Open surface area 3.85 sq. in UV inhibitors help prevent cracking and fading due to exposure to the elements