9 inch x 9 inch , Green, Square Grate, Made Of Structural Foam Polyolefin With UV Inhibitors, Open Surface Area Is 39.50 SQIN With 51.75 GPM, Use With The 9 inch x 9 inch Catch Basin Series, It Is Rated A Class B Load, Which Is Recommended For Medium Duty Pneumatic Tire Traffic, Autos and Light Trucks At Speeds Less Than 20 MPH.