DT Swiss Sram XDR Drive Ratchet EXP Freehub with End CapThe DT Swiss Ratchet EXP freehub system, especially when used with an XDR driver body for SRAM road cassettes such as Rival, Red and XPLR, offers a lightweight and reliable way to engage and disengage the drivetrain. The "EXP" stands for "Easy to Replace Parts" and highlights the system's design for easy maintenance. This system is favored by riders for its smooth engagement, minimal rolling resistance, and ease of maintenance.