Shimano RD-4700 Tiagra 10-Speed Rear Derailleur, SS Offering pro-level features, the 10-speed compatible Tiagra rear derailleur gives high performance at a low price Wide link design increases rigidity and service life Advanced light action for low-friction shifting up or down the block Alloy body's and outer link leads to lower weight without compromising strength and durability 11-tooth pulleys for reduced pulley wear and chain noise Two fluorine-coated link pin bushings for low-friction performance For double chainsets with 28 tooth max cassette Compatible with 4700 10-speed double road drive systems only