Like the valves, the retainers and locks are also titanium. Titanium retainers used to be notorious for having an extremely short service life, but Viccaro says that new coatings have significantly increased the durability of titanium retainers. This retainer has a coating that gives it a slightly rough, gray surface. Also notice that the locks have only a single, small bead to clamp onto the valve stem. When the valve stem is only 6 mm in diameter, you can't have a very deep locking groove. Because of this, Viccaro says it's critical that you keep your valvetrain under control.