The Shimano GRX RD-RX820 2x Rear Derailleur offers versatile performance, compatible with 11-34t and 11-36t 12-speed cassettes for a wide gear range. Navigate rough terrain with silent and secure shifting, thanks to the integrated chain stabilizer. The adjustable stabilizer prevents chain slap and drops, complemented by the Shimano Shadow RD+ for a distraction-free, quiet drive train. The ON/OFF stabilizer switch adapts to terrains, ensuring smooth and reliable shifting on mixed surfaces. Compatible with HG 12-Speed Chains, this derailleur combines reliability and adaptability for your cycling experience.