70 FSAU02 FSAU04 FSAU09 FSAU15 FSAU25 FSAU40 FSAU55 This post contains affiliate links . According to gpt: The main reason to step up to the XX PRO is if you want a more premium trainer for serious indoor training, rather than just a good-value direct-drive setup. Both models support smart training and work with cycling software using Bluetooth/ANT+ protocols. The X2 MAX is still more than enough for most Zwift / MyWhoosh / Rouvy users, particularly at this price, while the XX PRO makes more sense if you want the more premium trainer or care about power accuracy and ride simulation.