Hedman 68236 Headers For Select Chevy Passenger Short Block Cars Designed for Chevy/Bel Air/Biscayne/Impala, small block Headers are made from steel with a ceramic coat Full-length headers with a 1 5/8" primary tube size and 16-gauge and the diameter is 3-inch Collector is attached with a ball and socket standard flange Kit includes bolts, gaskets and reducers