NGK Iridium IX spark plugs are specifically designed for the performance enthusiast. Iridium IX provides outstanding acceleration, high fuel efficiency and durability. NGK Iridium IX plugs offer extreme ignitability and exceptional anti-fouling. Tapered cut ground electrode provides improved starting, idling and throttle response. The Iridium fine wire center electrode's durability is six times harder than platinum. Iridium alloy's extremely high melting point is perfect for today's engines. For even greater performance consider upgrading to an NGK Ruthenium HX plug. NGK Iridium IX spark plugs are specifically designed for the performance enthusiast. Iridium IX provides outstanding acceleration, high fuel efficiency and durability. BMW M3 1991-88, M5 1988, M6 1988-87, ATV - 2005-1998 ARCTIC CAT, 1985-1984 KAWASAKI, 2006-2000 MIDWEST, 2007-2005 MOTOFINO, 2008-1985 SUZUKI, 2008-1983 YAMAHA, M/C - 1998-1984 BMW, 1978-1971 HONDA, 2006-2000 MIDWEST, 1984-1981 YAMAHA