Shimano tiagra 4601 10 speed rear mechoffering pro level features the 10 speed compatible tiagra rear derailleur gives high performance at a low price featureswide link design increases rigidity and service lifeadvanced light action for low friction shifting up or down the blockalloy bodys and outer link leads to lower weight without compromising strength and durability11 tooth pulleys for reduced pulley wear and chain noisetwo fluorine coated link pin bushings for low friction performance32