Denso Double Platinum Spark Plug Triple platinum plugs offer long life and are typically called for on a Distributorless Ignition Systems (DIS). The platinum tip on the center electrode offers extended life, however the ground electrode has a double thick platinum tip for twice the life. This creates a long life plug with virtually no gap erosion, so that you will have optimum performance, longer. Copper core for better thermal conductivity. Machine rolled threads to reduce cross-threading and seizing . The plug insulator is constructed of purified alumina powder for extreme stress with 5 ribs to prevent flashover. Technical Specifications - 14mm Thread, 19mm (3/4") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Solid Terminal, Double Thick Platinum-tipped Ground Electrode and Platinum-tipped Center Electrode, Projected Tip, .044" (1.1mm) Gap