Keep the drainage system clear of debris with the trench drain grate. This ductile iron grate features a longitudinal bar design and an NDS Class C load rating when properly installed. This drain cover has an open surface area of 49.6 sq. in. per meter and flow rate of 152 GPM. ADA compliant and heel-proof channel grate. Two half-meter (19.69 in.) grates are required to cover one BG-FILCOTEN 100 4 in. trench drain. Iron grates are painted black to inhibit rust; over time, it will form a protective iron-oxide patina.