The Yamaha SEAT has five products enlisted in the schematic.
Parts such as the Seat: Cover, Single Seat, Nut(661), Washer(6a1), Single Seat Assy are included in the Br250ts Bravo 1992 Seat parts fiche.
The most reasonably priced component used on the Br250ts Bravo 1992 Seat is the Washer(6a1).