"Spark plug wires for Softail 2000-later and Dyna 1999-later, black. Designed by Sumax and made by Taylor, these 10.4mm pro race wires measure a shopping .409"" O.D. and include a spiral wound resistor type core. They are recommended for the most electronic ignition systems, but also work extremely well for point type ignitions. The core is covered with a pure silicone inner insulator and surrounded by a fiberglass braid for good pull strength. An 8mm O.D. pure silicone jacket is then added with a lightly woven heat resistant skin."