TEGIWA Flat Gaskets. These gasket form a perfect seal between two flat flanges. They are universal so can be utilised on pretty much any exhaust system, and will eliminate any blows or leaks that may be occurring from the joint. We offer four sizes - 2" triangle, 2.5" triangle, 2.5" oval, and 3" oval. The bore size is measured accross the internal diameter of the centre hole.