The great value ST-R7170 105 Wireless hydraulic disc brake Di2 STI's give you control, modulation and power with minimal effort in all riding conditions. Full 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 ratio.Wireless connectivity to the front and rear derailleurs for effortless trouble free gear shiftsWith 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 gearSimply 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 provides excellent stopping powerHydraulic 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 yearsKit contains bled ST-R7170 STI, BR-R7170 flat mount brake callipers with pads, hoses and mineral oil (without rotors or adapters)