NGK 4551 BR9HS-10 Nickel Spark Plug NGK standard plugs are constructed for longer life and optimum performance. Trivalent metal plating provides superior anti-corrosion and anti-seizing properties Corrugated ribs prevent flashover Pure alumina silicate ceramic insulator, provides superior strength and better heat transfer Copper core aids in heat removal Triple seals prevent leakage Product Specifications Shell Thread Diameter14mm Thread Pitch1.25mm Seat Type Gasket Reach12.7mm (1/2") Hex Size13/16" (21mm) Terminal Type Removable Nut Overall Height ISO Gap.039" (1.0mm) Center Electrode Material Nickel Type Standard Size2.5mm Projection non-Projected Ground Electrode Material Nickel Type Standard Quantity1 Specifications Resistor Yes Resistor Value5k Ohm Heat Range9 Torque Specs: Cast Iron: 18-25.3 lb. ft. Aluminum: 18-21.6 lb. ft.