The Rubber Gasket is the cheapest item from this partsfiche.
Parts such as the Kit Alarm Sys: Averto Alarm Unit, Collar Alarm, Led Lamp Unit, Tape 30 X 70 X 0,8 are included in the Cb600f Hornet 2010 (a) France / Cmf 25k Kit Alarm Sys parts fiche.
In this schematic the "Collar Alarm" is used most often.