The SRAM X01 drivetrain carries on the tradition of SRAM’s championship-winning 1X™ philosophy—all the way down the mountain. The setup is simpler. The drivetrain is lighter. & the shifting is fast & solid. Bottom line: X01 is the right one for any terrain, every time. X-Dome X-DOME technology creates an incredibly lightweight, precise & strong cassette. The open design aids in mud clearance, giving you cleaner shifting performance & longer component life. XD Driver Body XD is a new cassette driver body design that allows the use of a 10 tooth small cog & provides an enhanced interface with the cassette.