The Beru Glow Plug Kit - 135138 is a comprehensive kit of products designed for cars. It includes a set of glow plugs, which are essential components for diesel engines that help with cold starting. The kit also contains a glow plug controller, which regulates the power supply to the glow plugs and ensures they are functioning properly. Additionally, the kit includes a glow plug relay, which is responsible for activating the glow plugs at the right time. Finally, the kit contains a set of wiring harnesses and connectors to ensure proper installation of the glow plugs and related components. This kit is a convenient and cost-effective solution for maintaining and servicing the glow plug system of a car.