Sumax 8MM Black Silicone StreeThunder Spark Plug Wires ST231 500 ohm per foot resistance delivering greater spark energy, while improving power, idle, and fuel efficiency A combination Kevlar Helically Spiral Wound Core conductor for greater strength and durability that suppresses Electro Magnetic (EMI) and Radio Frequency Interference (RFI) Matching Black Silicone Boots protects against high exhaust temperatures Double Spring Locking Terminals for secure-vibration proof connections Low resistance conductor that is wrapped in durable silicone double layer jacketing for heat protection, strength and durability