Onyx Vesper Rear Hub - 12 x 142mm Center-Lock Black 28H XDROnyx Vesper Rear Hub 12 x 142mm Center Lock Black 28H XDR. Onyx Vesper hubs transfer the precise amount of torque you want to the ground when you need it. Nasty climbs on boulders and rock require just the right amount of instantaneous power but only at your command. There is no substitute for absolute control of your machine. Uphill or downhill Onyx ceramic hybrid bearings get you rolling faster and with less effort. Vesper hubs are the lightest MTB