The standard body of a Tacx direct drive trainer is not compatible with all cassettes. Use this body to suit your SRAM XD-R cassette. It is easy to replace, and all you need is a 5 mm hex key. The SRAM XD-R body is suitable for 11- and 12-speed SRAM XD-R cassettes. Type 1 Freehubs fit direct drive models built before September of 2019, Type 2 fit all modes built afterwards.