This is the factory inlet fitting used on Ford and International Harvester / Navistar products with 6.9 and 7.3 IDI engines and is used to connect the hard line from the fuel filter to the nose cone on the injection pump. These replace ones that are often lost or damaged during pump handling, or if you have damaged the threads on the one you have. This fitting comes with a new O-ring seal already installed on the inlet end. If you need a new "Olive" seal for your hard line, we have those too, and they do come in our Advanced injector installation kits, but it does not come with THIS part.