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. Header-Box U-Groove Ground Electrode Five-Rib Aluminum Insulator Copper Core Nickel/Chrome Steel Electric Heat Seal Copper-Glass Gas-Tight Seal Less Flame Dissipation Additional Attributes: GTIN: 00743047113059 Assembly Method: Gasket (Flat) Gap Size: 0.035 in. Hex Size: 0.625 in. Material: Copper Package Quantity: 4 Projected Tip: Yes Reach: 0.750 in. Resistor: Yes Thread Size: 14mm WARNING CA Proposition 65: No Extened Information: Emissions : Emission verification to be determined in ACES, vehicle application data. Life Cycle Status: Available To Order Packaging: Quantity of Each: Package UOM: Dimension: 0.9000 x 3.6000 x 4.9000 inches