These exhaust block-off plates work great when storing or shipping crate engines. We took the shape of a header gasket, deleted the ports, and made it out of corrosion protected electro-galvanized sheet metal. Just bolt it to the exhaust side of the head, (just like you would a header flange) and the exhaust side of the engine is completely sealed for either shipping or storage. We supply these in a set of 2/package, enough to do one complete engine.