The DENSO Iridium Tough Spark plugs have a 0.4mm iridium alloy electrode and a 0.7mm needle type platinum alloy ground electrode.

The quenching effect has been decreased by forming the electrode into a double needle shape. As a result, the flame kernel rapidly develops and the engine’s power is drawn out to its maximum potential.

Electrode design for the Iridium Tough

1. 0.7mm Needle shaped Platinum Ground Electrode. In order to maximally  prevent quenching effect, the ground electrodes could not be made too small without reducing grounding strength or increasing electrode wear.

2. 0.4mm Ultra-fine Iridium centre Electrode. Using DENSO’s exclusive  iridium alloy having a very high melting point, the tip of the centre electrode  can be shaped very thin and fine, reducing spark voltage requirements and  greatly improving ignitability.