Pro Copper Annealed (Soft) Copper Header Gaskets for 396-454ci Chevrolet Big Block with stock iron exhaust manifolds. Port Size: 1.85″ x 1.85″ with rounded corners. Gasket Thickness: .062″; Material: Flat annealed copper. These gaskets fit the same application as part number 4113 but do not have an embossed ridge around the ports. Package Contents: 1 Pair.