Bosch USR7AC Super Spark Plug, (Pack of 1) Heavy Duty Yttrium-Enhanced Center Electrode with Copper Core Provides Superior Reliability and Durability; BOSCH RSR7AC Spark Plug, Pack of 1 Tapered Cut Nickel Chromium Ground Electrode Assists in Cold Weather Starts and Provides Increased Ignitability Nickel-Plated Rolled Threads Provide Anti-Seize and Corrosion Protection Metal Glass Fused Resistor Gives Maximum Interference Suppression Angular, 5-Rib Insulator Design Prevents Flashover