The Honda B-series engine uses a 'Donut' style exhaust manifold gasket which allows the flange at the front of the cat / decat to pivot without leaking. This is a replacement 2.5" version which is regularly found on the Integra DC2 B18c Type-R and EK9 B16b Type-R engines and many aftermarket exhaust manifolds.
* Please check the size you need as many B series cars have had parts changed over time and may not be still using the standard size of 2.5" (63mm) inside diameter.