Fits 1955-1991 Chevrolet 262-400 Gen I Small Block. Round Ports. Perfect for Hooker/Stahl combination adapter plates;Manufactured from high-temperature steel core/graphite faced exhaust material; Expanded steel core provides stability and maximum torque retention to eliminate gasket failure; Graphite impregnated facing provides excellent heat resistance and thermal conductivity to transfer heat away from the cylinder head; Conforms to and seals minor surface irregularities; Can be trimmed if necessary for modified port applications; For OE replacement, high performance street, drag race and oval track use;