Copper Spark Plug 425 Autolite Copper spark plugs are engineered to deliver quick starts and the power your vehicle or applications needs to meet performance expectations. The copper core center electrode aids in thermal control and improves resistance to fouling. Its specially engineered high nickel alloy center and ground electrode provides extended life. The high alumina multi-rib ceramic insulator provides thermal conductivity and superior insulation for increased strength. Designed with a nickel-plated shell that is corrosion resistant to provide increased durability for extended periods. Center Electrode Design: Standard Center Electrode Tip Material: Nickel Ground Electrode Tip Design: Not Tapered Ground Electrode Tip Material: Nickel Hex Size (Inch): 13/16 Thread Diameter (Millimeter): 14 Reach (Inch): 0.5 Seat Type: Gasket Pre-Gap Size (Inch): 0.03 Manufacturer Heat Range: 8 Resistance (Ohm): 5000 Center Electrode Projection: Short Projection Terminal Type: Removable Nut