Mountain biking by nature is hard on its tools. The freehub body is no exception. After a few good hard years, it's not uncommon to see them wear out. Thankfully, it's a rather easy fix. The Mavic MTB Freehub body fits all 135mm spaced Mavic mountain bike wheelsets in their lineup above the CrossTrail Disc (which uses the same freehub body as the Mavic Shimano road wheels). So the CrossMax SL, ST, SLR, SX, etc. would all use this freehub.