The Hitachi High Pressure Fuel Pump Kit - 135939 is a comprehensive set of products designed to service a car's fuel pump system. It includes a high pressure fuel pump, which is responsible for delivering fuel to the engine at the correct pressure for optimal performance. The kit also includes various other components such as fuel injectors, fuel filters, and fuel lines, to ensure that the entire fuel system is functioning properly. Additionally, the kit may contain gaskets, seals, and other small parts necessary for installation and maintenance. This kit is designed for professional mechanics or experienced car owners who are familiar with the workings of a car's fuel system. It is a convenient and cost-effective solution for maintaining and repairing a car's fuel pump system.