(Stopper (0.7mm thick, 97mm bore)) Built for the (03-05) Nissan 350Z... Overview:HKS metal head gaskets are constructed from multiple layers of steel to ensure proper head to block sealing, even under the most severe conditions. The special metal used in the construction of the head gaskets is resistant to both heat + corrosion. All gaskets are coated with a special fluorine rubber coating to provide the ultimate sealing. MK4 Supras use the stopper type head gasket, the top one in the picture. The stopper type is the most effective + consists of the maximum layers of plates for the best possible seal. This head gasket is 1.6mm thick over 88 boreThe Stopper-Type gasket consists of the maximum layers of plates possible and utilizes a molded stopper ring around each combustion chamber opening.The Bead-Type gasket features a raised bead structure around each combustion chamber to ensure a precise seal.