661LG - Light Gray Plastic Dura Slope Channel Drain Grate - 6" x 24"NDS 661LG Light Gray Plastic Dura Slope Channel Drain Grate 6" x 24" Protect your drainage system from clogging with the Dura Slope Channel Drain Grate. The drain grate works with the Dura Slope Channel Drain to capture water flows from hardscapes while blocking leaves and debris in the water from entering the channel and potentially obstructing drain pipes. The drain cover has an open surface area of 25. 40 sq. in. per linear ft. and flow rate of 27.