Pro-Series, 8" x 20", Light Traffic Channel Grate, For Class B Loads Of 61-175 PSI. Recommended For Medium-Duty Pneumatic Tire Traffic, Autos And Light Trucks At Speeds Less Than 20 M.P.H. HDPE-High Density Polyethylene. Light Gray. Use For 8" Pro Series Channel. Grate Opening 5/8" x 2".