Parts such as the Clutch: Boss, Clutch, Plate, Seat, Circlip(10w), Nut (4x7) are included in the Xt660r 2006 5vk6 England 1e5vk-300g2 Clutch parts fiche.
In this schematic the "Plate,clutch 2 Steel Plate" is used most often.
Of all the components used in this assembly the Boss, Clutch is the most expensive.