The high-performance Shimano Ultegra ST-R8170 Di2 STI Hydraulic Disc Brake Lever gives you control, modulation and power with minimal effort in all riding conditions. Wireless connectivity to the front and rear derailleurs deliver effortless trouble-free gear shifts.Shimano Ultegra ST-R8170 Di2 STI Hydraulic Disc Brake Lever FeaturesWith Di2 technology shifting is easy and precise - just a light touch, as soft as a mouse click, is sufficient for the front or rear derailleur to instantaneously select the correct gearFull and semi synchronized shifting programable, Synchro shift compatible meaning a single shifter can control both front and rear shifting which can be fully custom tuned to your riding preferences. Semi synchronized shifting means when a front shift is made the rear mech will automatically correct to the appropriate ratioSimply pressing tactile buttons allows effortless and comfortable shifting even when your hands are coldDrop bar STI with shift buttons located in a near identical place to the positions you'd assume shifting using a mechanical Shimano STIHydraulic brake lever with Servo Wave provides excellent stopping power with less effort especially from the hood positionHydraulic reservoir tank provides pad to rotor clearance auto-adjust maintaining braking performance during pad wearFinely tuneable reach adjusters for the levers enable custom fitment for all handsLevers use CR1632 batteries which last for approximately 1.5-2 years