Denso (5358) IK20L Iridium Power Spark Plug, (Pack of 1)

Increased performance with World's smallest Iridium Center Electrode (0.4mm). To increase ignitability, the important point is to let the flame kernel produced by the spark to grow unobstructed. Normally, this can be accomplished by widening the spark gap. However, this causes spark voltage to increase, which has the opposite effect. Iridium Power uses DENSO's patented U-Groove ground electrode to achieve maximum ignitability while minimizing required voltage.