Campagnolo 12 Speed Bicycle Rear Derailleurs
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."
The number of speeds should correspond to the number of cogs on the cassette.