Protect the drainage system from clogging due to leaves and debris with the trench drain grate. This ductile iron grate with longitudinal bar design boasts an NDS Class D load rating when properly installed. The drain cover has an open surface area of 73.63 sq. in. per meter and flow rate of 226 GPM. ADA compliant channel grate. Two half-meter (19.69 in.) grates will 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.