Mr. Gasket copper seal collector gaskets are made from solid 0.043`` thick copper. This gasket incorporates 0.051`` in embossment around each port to seal irregular surfaces, total gasket thickness is 0.094``. Provides excellent sealing and durability. Conforms to and seals minor surface irregularities. Designed for high-performance street, drag race, oval track and turbo-charged (extreme heat) applications.