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. Bolt supplied will be for German A fork, the smallest of the four available sizes. (picture is of the larger bolt for steel forks)