The Nut,lock,flanged,6mm is the lowest priced item on this Rear Fender schematic.
A sample from the products for the Rear Fender include: Damper,6x10x15, Bracket,reflector,lh, Band, Nut,lock,flanged,6mm.
In this schematic the "Nut,flanged,6mm,black" is used most often.