Prevent debris from entering and clogging the drainage system with the trench drain grate. This sturdy ductile iron grate, or drain cover, has a slotted design with openings that span the width of the grate and has an NDS Class E load rating when properly installed. It has an open surface area of 72 sq. in. per meter and 221 GPM flow rate. 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 and over time will form a protective iron-oxide patina.