This cover plate can be used to block off the intake manifold EGR (exhaust gas recirculation) outlet for all 1994-05 Miata. On 94-97 and 01-05 Miata, this cover plate must be used along with the Racing Beat EGR cap and the factory EGR pipe can be removed. On 99-00 Miata, the cover plate must be used with the Racing Beat EGR Plug.