The Carbon Onyx and the Copper Carbon Classics are manufactured differently than the hollow-fiber Fiberreeds. They are made of epoxy infused with carbon and copper fibers. The Carbon Onyx are more free-blowing, bright and clear whereas the Copper Carbon Classics have more resistance and produce a somewhat darker, rounder tone. High register and altissimo are solid for both models. Playability and response are very similar to the hollow-fiber models but with less buzz.