Shimano ST-R7120-L is a left-side 2×12 road shifter and hydraulic disc brake lever for Shimano 105 R7100 mechanical drivetrains. It is designed for drop-bar road bikes and is intended for the front derailleur on a 2-speed setup, making it a good fit for riders building or replacing the left brake/shift lever on a 12-speed Shimano road drivetrain. Shimano describes the lever design as updated for better reach and comfort, with a shorter lever access curve for a wider range of hand sizes.