With its integrated chain stabilizer, the SHIMANO GRX rear derailleur delivers quieter shifting and more secure chain management in rough terrain. The RD-RX822-SGS is compatible with 10-51T, 12-speed SHIMANO MTB cassettes, meaning you’ll never run out of gears even on the steepest jeep road or high mountain singletrack ascent. And the chain tensioner has an ON/OFF switch for easy wheel removal.