The Fuel Injector and Oil Rail O-ring Kit is a high-quality replacement kit for 2003-2007 6.0L Ford Powerstroke engines. This kit includes the complete external fuel injector o-rings and oil rail ball tube o-rings, which are critical components in this fuel injection system. The oil rail o-rings are used to seal the fuel oil rail pucks or ball tubes, and the external injector o-rings include all major components such as the high pressure top o-ring and copper washers needed for installation. They are made of viton, which is considered the most durable material for use in diesel engine applications. All o-rings are designed to withstand the high pressures and temperatures of the engine. This o-ring kit is easy to install and is a direct replacement for the factory parts. With a one year unlimited mileage warranty, you can trust that it's built to last. Replace your worn or damaged o-rings with this high-quality replacement kit and keep your engine running smoothly.