The Second Air (e18) is made up of components including this Valve Assy,2nd Air Reed which is the most expensive.
Parts such as the Second Air (e18): Pipe,2nd Air,l, Valve Assy,2nd Air Reed, Gasket,second Air Pipe (nas), Bolt are included in the Gsf600s 1999 (x) (e02 E04 E17 E18 E22 E24 E25 E34) Second Air (e18) parts fiche.