The GX Type 2. 1 10-Speed Rear Derailleur packs all of SRAM's favorite two-by engineering into a smooth, reliable, and accurate shifting without burning a hole in our pocket along the way. The steel pulley bearings are paired with the aluminum cage to offer lasting durability, a hallmark of the GX line, as you transition from rock gardens to gravel pits. The popular Roller Bearing Clutch is also present, delivering maximum stability through the drivetrain by maintaining consistent tension on the chain. The rear mechanism is finished SRAM's Cage Lock technology that keeps the derailleur locked out of the way for simple rear wheel installation and removal.