The Shimano Ultegra ST-R8170-L is a left-side combination lever integrating a hydraulic disc brake with a 12-speed electronic Di2 shifter designed for road bikes. It features Shimano’s SERVO WAVE brake technology, which provides a lighter and smoother lever action with improved brake modulation, enhancing control during rides. The shifter employs wireless and wired connectivity options for flexible installation and compatibility with other R8100 Ultegra Di2 components, including satellite shifters. It uses easy-to-change CR1632 coin batteries that last about 1.5 to 2 years. The lever is constructed with an aluminum body and carbon fiber Di2 shift pads, finished in dark gray, and optimized ergonomically with raised hood peaks for better grip. This component is ideal for riders upgrading to or maintaining a 12-speed Ultegra Di2 hydraulic disc brake system who want precise, reliable electronic shifting and responsive braking integrated into a clean cockpit setup. It is compatible with Shimano Ultegra R8100 12-speed groups and supports a fully wired or wireless Di2 road system installation.