Prevent leaves and debris from being swept into the drain system with a trench drain grate. This grate made of polyamide plastic has a unique COMBee design, much like a honeycomb. The grate, also known as a drain cover, has an open surface area of 44.95 sq. in. per meter and flow rate of 138 GPM. The grad has an NDS Class C load rating and is ADA compliant and heel proof. To cover one BG-FILCOTEN 100 4 in. trench drain, use two 1/2 meter (19.69 in.) grates.