Denso Platinum TT spark plugs feature a twin-tip design, allowing for a more efficient combustion, which yields better engine performance in terms of power and fuel economy. 1.1mm platinum tipped center electrode and titanium-enhanced 1.1mm ground electrode. Machine rolled threads prevent seizing or cross threading during installation and removal. 100% pre-fired to assure the highest quality possible. Purified alumina powder insulator provides exceptional strength and thermal conductivity. Five rib insulator prevents flashover. Copper-glass seal bonds center electrode and insulator for a gas-tight seal. Shell Thread Diameter: 14mm Thread Pitch: 1.25mm Seat Type: Gasket Reach: 19mm (3/4") Hex Size: 5/8" (16mm) Terminal Type: Solid Overall Height: ISO Gap: .039" (1.0mm) Center Electrode Material: Platinum Type: Fine Wire Size: 1.1mm Projection: Projected Ground Electrode Material: Titanium Type: Fine Wire Quantity: 1 box Specifications Resistor: Yes Resistor Value: 5k Ohm Heat Range: 16 Torque Specs Cast Iron: 26-30 lb. ft. Aluminum: 15-22 lb. ft.