The Shimano 105 RD-R7150 Di2 12-speed rear derailleur completes a shift in the blink of an eye with its high-performance motor and optimized link structure. This is the hub of the Shimano Di2 system, with the charging port, indicator LEDs, adjustment switches and more integrated into a compact package. - Low-profile Shimano Shadow RD design reduces damage from contact and falls - Receive the wireless shifting signal from the shift lever - Check the battery level and Bluetooth/ANT pairing success with your cycle computer/smartphone/tablet - Allows selection of preferred shift mode and view adjustment mode information (if you wish to tweak or tune your rear derailleur) - Smartphone/tablet connectivity via E-TUBE PROJECT Specs - Largest Cog: 36 - Rear Derailleur Mount Type: Shimano Rear Direct Mount , 10x1 Standard - Chain Wrap Capacity (teeth): 41 - Rear Der/Shifter Compatibility: Shimano Road Di2 - Drivetrain Speeds: 12 - Weight: 302g