This shimano cx75 ultegra centre lock disc rear hub is a cold forged aluminium hub for serious road and cyclocross riders with improved sealing performance through the use of low friction labyrinth and contact seals and an internal grease sleeve using a special boron nitride machining process that has been applied to the cones to make them rotate super smooth designed to be used with either shimano centre lock disc rotor mount for secure hassle free setup or regular rim brake the cx75 rear