The standard freehub body of a Tacx direct drive trainer is not compatible with all cassettes. Use this body to suit your Campagnolo cassette. It is easy to replace, and all you need is a 5 mm hex key. The Campagnolo body is suitable for 9- through 12-speed Campagnolo cassettes. Type 1 Freehubs fit direct drive models built before September of 2019, Type 2 fit all modes built afterwards.