Stainless Steel Marine™ spark plugs are the ultimate performance solution for marine engines. With a stainless steel shell, this unique spark plug is impervious to rust over the life of the plug. The copper core ground electrode dissipates heat faster resulting in less gap erosion. In addition, it provides smoother idle, better fuel economy, and helps prevent engine damaging preignition. Thats why you get peak performance all season. The Q-type suppressor eliminates RFI related false readings on depth/fish finders, GPS and other navigational instruments. This also eliminates static in audio and on-board communications systems—all achieved with no loss of ignition performance.