The Genuine VW / Audi Glow Plug Kit - 178357 is a comprehensive kit of products designed for use in a car. It includes various components that are essential for the proper functioning of the car's glow plug system. The kit contains a set of glow plugs, which are small heating elements that help to ignite the fuel in a diesel engine. It also includes a glow plug relay, which acts as a switch to control the flow of electricity to the glow plugs. Additionally, the kit contains a glow plug harness, which is a wiring system that connects the glow plugs to the battery and the engine control unit. Other components included in the kit may vary, but they typically consist of gaskets, seals, and other necessary hardware for installation. This kit is specifically designed for use in Volkswagen and Audi vehicles, but it may be compatible with other makes and models as well.