Disc brake lever/rear derailleur kit for ULTEGRA Di2 12V range and rear brake caliper. Includes: ULTEGRA ST-R8170 ergonomic dual control shifter brings new levels of comfort and control to road cycling. With the most rapide wireless shifting on the market. The Di2 platform, used on DURA-ACE and ULTEGRA models, frees up gear shifting while offering more reliable rapide wireless shifting. The ULTEGRA R8170 disc brake caliper brings a new level of control to the world of road cycling with improved modulation and a more rapide initial braking point. With improved modulation, a quieter braking system and an easier bleeding process than ever before. Approx. caliper weight: 123 grs. Lever weight approx. 196 grs.