SHIMANO Ultegra Di2 R8050 Short-Cage Rear Derailleur;

Thanks to Shimano's penchant for trickle-down technology, you can get Dura-Ace functionality at a more attractive price point. As long as you don't mind the slight weight differential you can count on Ultegra to serve up shifts that are every bit as clean, smooth and precise as those Dura-Ace delivers. For 2017, Shimano uses their shadow design, for a thinner assembly construction to offer a more streamlined, integrated fit. The pulley maintains consistent distance to the cassette for increased shift stability, and is compatible with a cassette up to 11-34T.Features: Shimano synchronized shift System communication with front derailleur Stable Shifting Performance Shimano Shadow Construction Low profile rear design Uses up to an 11-34T cassette