Shimano GRX ST-RX610 Shift/Brake Lever with BR-RX410 Hydraulic Disc Brake Caliper - Left/Front 2x Flat Mount Caliper Black. The Shimano GRX ST-RX610 dual control lever delivers light and responsive shifting for mixed-terrain riding. The textured hood and anti-slip brake lever surface increase control on bumpy terrain. The RX610 shift/brake lever is paired with a GRX BR-RX410 flat mount disc brake caliper that brings a new level of control to gravel cycling with enhanced modulation and a quicker initial braking point. And despite its compact construction the system is quieter and easier to maintain.