If you're running a DT Swiss 180, 240, 350, or 440 Ratchet rear hub, and you damage your freehub body, or simply want to swap from a SRAM XD drivetrain to an HG, you'll want this, the DT Swiss Ratchet Freehub Body. This freehub utilizes the company's famous Ratchet system, ensuring the durability you've come to expect from DT Swiss.