Clear Opening 500 mm Heavy Duty Item No.: GRC-3011-C Loading 40 tonCover Material: Gray IronLength Cover: 870 mmWaterway : 1957mm2The Frame Made of Rolled Steel Options Heavy Duty Item No.: GS-2009-C Loading 40 tonCover Material: Gray IronLength Cover: 610 mmWaterway : 1344 mm2The Frame Made of Rolled Steel Options Medium Duty Item No.: GS-2010-C Loading 15 tonCover Material: Gray IronLength Cover: 610 mmWaterway : 1344 mm2The Frame Made of Rolled Steel Options