Kit Content:4 x Denso COP Direct Ignition Coils4 x NGK Ruthenium HX Spark PlugsItem Description:Thread Diameter(mm): (Spark Plugs) 14.00Center Electrode Core Material: (Spark Plugs) CopperElectrical Terminal Type: (Spark Plugs) Non-Removable NutGround Electrode Quantity: (Spark Plugs) 1Center Electrode Tip Material: (Spark Plugs) RutheniumInsulator Height(mm): (Spark Plugs) 50.50Ground Configuration: (Spark Plugs) StandardVoltage(VDC): (Direct Ignition Coils) 12Reach(in): (Spark Plugs) .75Ground Electrode Core Material: (Spark Plugs) NickelResistance(Ohms): (Spark Plugs) 5000Color: (Direct Ignition Coils) GrayManufacturer Heat Range: (Spark Plugs) 5Ground Electrode Tip Design: (Spark Plugs) Dual Fine Electrode - High IgnitabilitySeat Type: (Spark Plugs) FlatHex Size(in): (Spark Plugs) 5/8Pre-Gap Size(in): (Spark Plugs) .044