For fast, reliable shifting during our mixed-terrain riding adventures, Shimano brings us the new GRX RD-RX825 12-Speed Di2 Rear Derailleur, complete with a built-in wireless connectivity unit and charging port for easy operation and recharging. SHIMANO SHADOW RD+ chain stabilization helps prevent chain slap to allow us to continue to shift accurately as we ride over rough terrain, while the switch stabilizer features an ON/OFF switch to match the terrain and ease wheel removal. Compatible with 11-34t and 11-36t 12-speed cassettes, this wireless rear derailleur is ready to be added to our dream gravel setup.