The Bolt.flang 6x12 is the lowest priced item on this Rear Brake Caliper schematic.
On this parts fiche the Insulator is the most specified component.
Parts such as the Rear Brake Caliper: Cap,bleeder, Pin,hanger, Piston, Retainer are included in the Cr250r Elsinore 1990 (l) Usa Rear Brake Caliper parts fiche.