Designed to operate over a much wider heat range than ordinary plugs. Resists carbon buildup and pre-ignition. High alumina ceramics for better heat transfer and electrical insulation. Solid copper core and nickel tipped electrode provide a longer life. Patented triple gasket sealing process eliminates the possibility of combustion gas leakage. Solid copper core for greater spark. Longer insulator nose prevents fouling. 14mm diameter, 3/4" (1.9cm) reach and 13/16" (2.1cm) hexagonal nut.