Bosch Duraterm Glow Plug Kit FOUR (4) GLOW PLUGS & ONE RELAY Bosch Duraterm Glow Plug Technology With a long history of diesel fuel injection expertise and innovation, Bosch leads the way in glow plug technology with its patented Duraterm dual-control coil design. This technology utilizes a self-regulating system that reduces glow wait time by more than 50%. The patented dual control regulating and heating coil system effectively directs current draw, enabling the glow plug to reach higher temperatures more quickly for faster engine start-up. For vehicles with a post-glow control system, this advanced technology results in a post-glow heating phase which allows for more efficient overall engine performance. Features and Benefits: Glow plug reaches higher temperatures more quickly for fast engine start-up Regulating coil controls current draw for rapid heat-up of heating coil Heating coil provides rapid heat-up of the glow tube and quick start-up Glow tube material resists corrosion and vibration for long service life Fine-grained ceramic insulating powder provides superior electrical insulation and high thermal conductivity Twin Viton® seals protect coils from exhaust gas damage for long life Connectors designed to OE specifications precise fit and easy installation