On this parts fiche the Washer,32x6.5x2.3 is the most specified component.
Parts such as the Seat: Bolt Flang 6x12, Washer,32x6.5x2.3, Bolt,flange,6x12, Holder,helmet are included in the Cn250 Helix 1996 (t) Italy Kph Seat parts fiche.
The Washer,screw 6x12 is the lowest priced item on this Seat schematic.