By harnessing the power of Iridium, Denso is able to shrink the surface area of the center electrode - the most critical component of a spark plug.  Unlike the typical platinum plug that has a 1.1mm diameter center electrode, the Denso Iridium Power spark plug as the world's smallest center electrode measuring only .4mm in diameter.

The spark plug can be an important tuning tool for your engine.  You use a hotter plug in cooler conditions and cooler plug in warmer conditions.  When you go from a cooler to hotter plug you are leaning out the motor slightly.

This is the recommended and spec. plug for Rotax. It's also suggested for use when racing CR125 Stock Honda.

The lower the number, the hotter the plug.