These Force AXS Flat Mount hydraulic disc brake calipers are designed as part of the HRD system used for road/gravel/cross bike set-ups with Force eTap AXS HRD levers. The simple looking two-piece alloy exterior of the caliper body hides a more evolved road disc brake system built on the HydroHC platform SRAM has created. The dual resin piston design is set-up to maximize the effectiveness and simplicity of the Bleeding Edge fluid system to move easily, delivering more modulation and control from the lever, which itself has been shaped to maximize power with low fade. Heat is properly managed and controlled by the DOT 5.1 fluid to actuate and control the effectiveness of the included steel-backed organic disc pads. The 119 gram Force AXS Disc Brake caliper is not specific to front or rear use, and is sold individually.