Shimano dura ace 7900 10 speed rear mech dura ace rear derailleur with lightweight carbon cage and wide link design gives quick accurate shifts and unmatched drivetrain efficiencyfeatures full carbon fibre inner and outer pulley plates enhance rigidity and significantly reduce weight high tolerance cold forged aluminium link plates and body construction provide for extremely light weight strength and durability high rigidity wide outer link plates the pulley body to increase pivot joint rigid