When we need to adapt our Tacx direct drive trainer to work with a different cassette, or perhaps just need a replacement freehub, this freehub body is what we need. Pairing Campy cassettes with Campy drivetrains, and likewise Shimano with Shimano and SRAM with SRAM ensures the best shifting performance. This is why we recommend keeping the cassette on your trainer consistent with the one that's already on your bike for the best overall experience. This freehub body works with the Neo and Flux series of trainers and features durable aluminum construction with a steel insert that helps prevent the cassette from notching up the freehub body.