NGK Marine Spark Plug Corrugated ribs Triple-Gasket sealing process Copper core For marine applications M/C 2005-1993 Aprilia, 1996-1991 Honda, 2003-1999 Husqvarna, 2001-1991 Yamaha, Pwc 2001-1997 Yamaha, O/B 2003-1977 Evinrude, 2006-1978 Johnson, 1981-1976 Spirit Suzuki, 2004-1996 Yamaha, Pe Engines Kohler, Lawnmower Solo, Water Pump Yamaha. Thread Size: 14mm