Retaining bolt that screws into the top of the fork to assist in securing the handlepost, there are four sizes of this bolt, one for steel forks, two for Aluminium forks and one that is only used on the Kinetix German A suspension fork (Jetstream) Note carefully which you require before ordering. This is the new type M23 bolt for Aluminium forks. If you have obtained new forks and find your original bolt does not fit, this is the bolt you need, as Dahon have increased the wall thickness of the steerer tube on the more recent models.