The Ford 6.7L Powerstroke factory high pressure injector fuel lines are subject to corrosion that can lead to injector issues. Anytime you are servicing your injectors, it is recommended that you check the lines for corrosion and replace them if necassary.  These are direct replacement lines from BD Diesel that are zinc plated, making these corrosion resistant. These lines will ensure the fuel being fed to your injectors is clean and contamination free.