Denso (4717) ITL16TT Iridium TT Spark Plug, (Pack of 1) Denso # 4717 0.4mm Iridium Center Electrode 0.7mm Platinum Ground Electrode Larger spark translates to more power and superior fuel economy 0.4 mm iridium center electrode: world's smallest diameter that maximizes firing potential 0.7 mm needle tip ground electrode: promotes higher spark energy and less heat quenching DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the iridium center electrode DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the iridium center electrode