6", Black, Square Structural Foam Polyolefin Grate With A Diagonally Converging Pattern, & UV Inhibitors, Open Surface Is 10.40 SQIN & It's 13.62 GPM, Fits 3" Or 4" Sewer & Drain Pipe, 3"or 4" Corrugated Pipe, & 3" Or 4" Triple Wall Pipe, Loads Of 1-60 PSI, Recommended For Pedestrian, Bicycles, & Wheel Chair Traffic.