This 45100-31g10-u3f is the most expensive of the items that make up this Seat assembly.
Parts such as the Seat: Cushion, Cushion, Seat Assy(blac, 45100-31g10-u3f are included in the Lt-a700x King Quad 2007 (k7) Usa (e03) Kingquad King-quad Seat parts fiche.
In this schematic the "Cushion" is used most often.