One Dozen (12) BPR6ES Spark Plugs Fits Chrysler & MerCruiser Inboard EnginesOne Set of Twelve (12) Brand New Aftermarket Replacement Fits NGK BPR6ES Spark Plugs Fits Chrysler and MerCruiser Inboard Marine Engines Solid Copper Core Aids in Heat Dissipation Corrugated Ribs to Prevent Flashover Triple Gasket Sealing Process Eliminates Gas Leakage Past the Shell 99% High Grade Pure Alumina SiliFits CATe Insulator Provides Better Heat Transfer and Superior Strength Cold Rolled Threads to Prevent Damage to Cylinder Head Trivalent