The Shimano Ultegra RD-RX800 RX Shadow+ GS rear derailleur with wide link design gives quick accurate shifts and excellent drivetrain efficiency. Shimano Ultegra RD-RX800 RX Shadow+ GS Rear Derailleur Features Shadow Plus uses a chain stabilising switch that when on will reduce chain bounce in rough terrain maintaining more stable drive and shifting Sleek appearance with Low profile Shadow design construction reduces risk of damage in a crash Wide outer link plates increase pivot joint rigidity to reduce shifting deflection Lightweight aluminium pulley cage helps reduce weight without sacrificing shifting performance Wide gear ratio compatible with 11-28 up to 11-34T