Replacement Engine Casing Plate.
Generator Guru says:
You will require a gasket kit to rebuild your engine. In a small engine, gaskets and seals are used in many locations to improve the seal between components. They are designed to prevent the fuel air mixture from leaving the cylinder during combustion. They are also used to keep oil from leaving the crankcase. These are two of the most critical functions gaskets and seals serve. One defective engine gasket or seal can cause a significant loss of horsepower. Make sure the surface is clean before fitting. Lightly use a razor blade to remove any residue until it feels smooth to the touch.