Spark Plug U-Groove Spark Plug Header Plug U-Groove Spark Plug Header Plug; Double Platinum Shorty; Individual; SPECIFICATIONS: Color: White Thread Size: 14mm FEATURES: Double Platinum Electrode For Long Life Shorty Spark Plugs For Tubular Exhaust Headers Eliminates Dimpling Headers For Added Clearance Improves Spark Plug Access To Fit Socket Or Wrench Shorter Overall Plug Length Vs. OE Style Plug Projected Tip Helps Eliminate Burned Spark Plug Boots Shorty Header Spark Plug Machine Rolled 14mm Threads Protect Your Valuable Cylinder Heads ACCEL U-groove performance spark plugs produce a larger spark for more power at high RPMs. Improves throttle response and fuel economy, less fouling. Purified alumina insulator prevents arcing. Machine rolled threads protect heads. For more than 40 years, ACCEL has been a leader in performance fuel and ignition systems, proving itself on the racetracks and drag strips of the world - and on the street. With an ever-expanding line of SuperCoils and all the spark plug wires, tune-up kits, and fuel injectors hot rodders have trusted and relied on for years, ACCEL is constantly developing innovative new products designed to push power, speed, and performance to match advancements in automotive technology. Now part of Holley Performance, ACCEL offers a comprehensive selection of performance products, including coils, digital fuel injection systems, fuel injectors, distributors, caps, rotors, ignition wires, spark plugs.