NGK tinned copper core wire sets provide excellent OE fit, performance and durability. High - temp premium silicone outer jacket and inner EPDMsilicone insulation contain high voltage currents for excellent dielectric strength. As required on certain European models, NGK utilizes a premium 29 gauge galvanized, tinned core core wire. RFI suppression is located close to the source and thus built into NGK's OE designed spark plug and distributor connectors and metallic resistor boots. Spark plug boots are glued to NGK cable with a silicone sealer for a watertight seal.