NGK spark plugs feature trivalent plating. This silver or chrome-colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal.
NGK Spark Plug
Part No. Recc. Horsepower Stroke B8HS-10 30-85 2 B7HS 40 2 DPR6EB-9 50-60 4