Nylon Interface Prevailing Torque Fasteners
WARNING: This page is about a different car, the 2005 Saturn Ion Red Line, 2005 Saturn Ion 3, 2005 Saturn Ion 2, and 2005 Saturn Ion 1. However, it is still accessible from the selected car via links, so may be relevant.
These fasteners accomplish the thread interface by the presence of a nylon material on the fastener threads.