BelMetric Star Lock Washers are available in a variety of body forms (Internal, External or Combined) and locking styles (Toothed Locking vs Serrated Locking).
Internal Star Washers have a smooth outer surface that will not catch or snag nearby items.
External Star Washers are best for larger head diameters to ensure the best locking grip; pan head, button head and truss head screws, etc.