Cometic MLX head gaskets (Multi-Layer-Steel-Stopper) features an extra 'stopper' fold-over layer providing a torque limiting surface that prevents yielding of the combustion seals. High temperature polymer along with embossments provide a micro seal for fluids against the head and block surface.
A surface finish of 50 microinches or finer is recommended for a proper gasket seal. Anything rougher may result in gasket failure.