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.