Parts such as the Rear Brake Mastercylinder (cb600f/f3): Nut,hex.,8mm, Washer,oil Bolt, O-ring,14.8x2.4, Cap,oilcup are included in the Cb600f Hornet 2007 (7) European Direct Sales / Type 2 Rear Brake Mastercylinder (cb600f/f3) parts fiche.
The most reasonably priced component used on the Cb600f Hornet 2007 (7) European Direct Sales / Type 2 Rear Brake Mastercylinder (cb600f/f3) is the Screw-washer,4x12.
In this schematic the "Washer,oil Bolt" is used most often.