Product Description Product Sketch Frame clear opening mm Frame Details Cover Details Overall size/mm Total Height/mm Thickness of seat/mm Overall size/mm Total Height/mm Extra Heavy Duty Circular Manhole 560 600 560x560 900x600 860 900 860x860 1200x900 175 175 175 175 75 75 75 75 705 745 705x705 7045x745 100 100 100 100 Heavy Duty Manhole Circular/ Square 500 560 600 560x560 900x450 800 860 900 860x860 1200x750 150 150 150 150 150 75 75 75 75 75 645 705 745 705x705 1045x595 75 75 75 75 75 Medium Duty Manhole Circular/ Square 450 500 560 450x600 650 700 760 650x810 100 100 100 100 50 50 50 50 545 595 655 545x695 50 50 50 50