The Shimano GRX ST-RX610 dual control lever delivers light and responsive shifting for mixed-terrain riding (Note: BR1057 is a left non-shift variation for 1x set ups) . The textured hood and anti-slip brake lever surface increase control on bumpy terrain. The GRX BR-RX400 2-piston flat mount hydraulic disc brake caliper features a low-profile design with ICE technologies to provide greater control and excellent heat dissapation for mixed terrain riding.