... spark plug.auto spark plug, motorcycle spark plug, truck spark plug, resistor spark plugs, iridium spark plugs, platinum spark plugs, ceramic spark plug, toroidal multi-electrode spark plugs, iridium-platinum spark plugs, multi-ground electrode spark ... . Ignitability and lifetime have been improved dramatically. SK16R-P11 comes standard with the Toyota Century. Iridium Spark plug SK16R-P11