" indicate the difficulty level for installing the product.A new generation of high-performance spark plug that uses the world's smallest electrodote. A mere 0.4mm in diameter.Iridium, a metal that has a 4,000 degree melting point, made this possible.A new generation of high-performance spark plug that uses the world's smallest electrodote. A mere 0.4mm in diameter.Iridium, a metal that has a 4,000 degree melting point, made this possible.