Shimano GRX RD-RX822-GS Rear Derailleur - 12-Speed Direct Mount Medium Cage Shadow Plus Design 45t Max Low

With an integrated chain stabilizer Shimano GRX RD-RX822 12-speed rear derailleurs feature an intergrated chain stablizer that delivers quieter shifting and more secure chain management in rough terrain. The chain tensioner has an ON/OFF switch for easy wheel removal.