Shimano RD-R9150 Dura-Ace Di2 Rear Derailleur 11 Speed

Di2 E-Tube Electronic Shifting
Ergonomic shifting operation without stress
Shimano Di2 synchronized shift
Cassette Spacing: Shimano/SRAM 11
Low profile rear derailleur design
Shimano Shadow Rear Derailleur: Keeps derailleur tucked away
Race endurance for less damage in crash
Maintains a compact and smooth appearance
Maximum Sprocket: 30T
Minimum Sprocket: 11T
Maximum Front Difference: 16T
Total Capacity: 35T
Weight: 204g.