NOW WITH 304 STAINLESS STEEL FLANGE
Note the cat pipes are usually 61-63mm OD whereas the exhaust box is usually 57mm OD . There are two options you can purchase Cat Repair with 63mm id section or Exhaust Box Repair with 57mm ID 
Due to age and corrosion, the exhaust and cat flanges can corrode and become an MOT failure due to leaks.
This repair kit will allow you to grind off the old top hat section and remove the damaged flange and re-weld the new stainless steel top hat section on.
This will be supplied with 1 new gasket and 3 bolts/nuts/washers.