Bitubo fork sliding kit S. The Bitubo Kit S for fork smoothness increases the smoothness of the fork by acting on the reduction of friction this occurs during braking when the structure of the fork in the compression phase undergoes a deformation called ovalization which causes an increase in friction. Beginning of the fork movement due to the gluing of the various components such as oil seals and bushings. The package includes: Specific assembly instructions for the motorcycle. Specific for: Honda CBR600F New no Abs 2011>2013. Pair of bushings in ergal 7075. Pair of fork stem oil seals.