Campagnolo 12 mm Thru x 142 mm Shimano/SRAM 8/9/10; Shimano Dynasys 11 Bicycle Rear Hubs
About Campagnolo - "Campagnolo puts all of its professionalism and expertise into the manufacture of its components in Via della Chimica plant in Vicenza. All production takes place exclusively within Campagnolo's own plants, so that product development can be a fully integrated part of the process. Every step in the process, from design and engineering to testing and industrialisation, takes place within Campagnolo facilities. Campagnolo even develops its own tools, machinery and technology so that it can produce only the very best components and wheels for racing bicycles."
This is hub spacing and is the width of the hub. It must match your frame specifications.
The cassette body type is the type of cassette and number of speeds the hub will accept.