The lowest price component in this F-6 parts-list fiche is the O-ring,2.8x1.9 (s.
Parts such as the F-6: O-ring,2.8x1.9 (s, Rubber,stopper, Protect*tnatural*, 0 Ring,18.8x1.9 are included in the Cr85r 2003 He07-100 Japan Jdm F-6 parts fiche.
On this parts fiche the Bolt,protector is the most specified component.