If you're running a DT Swiss 240, 350, or 440 rear hub, and you damage your 9/10-speed freehub body, or simply want to swap from a SRAM XD (1x11) drivetrain to a 2x or 3x 9/10-speed one, you'll want this, the DT Swiss Mountain Freehub Body. Compatible with all non-XD Shimano and SRAM drivetrains, its shell and internals are made by DT Swiss and utilize the company's famous Star Ratchet pawl system, ensuring the same level of quality as the hub to which you'll be installing it.