The Shimano XTR BR-M9100 hydraulic disc brake set represents the successor to earlier XTR brake systems and has been specifically designed for mountain bike applications. This right-side rear configuration features a robust black aluminum 2-finger lever. The hydraulic disc brake system uses mineral oil as the operating fluid and integrates a 4-piston brake caliper BR-M640 with post-mount compatibility. Key specifications include a 1700 mm short rear brake hose, tool-free adjustable reach, open clamp design, and one-way bleed capability. The brake set is equipped with D01S resin brake pads without cooling fins and is designed for use with recommended brake rotors such as the SM-RT68 or SM-RT66 models. The BL-M9100 brake lever provides precise modulation and consistent braking performance under various trail conditions. This component is intended for integration into high-performance mountain bike builds where reliable braking power and durability are essential requirements. The aluminum construction offers a balance of strength and weight efficiency, while the hydraulic system ensures consistent braking feel with minimal maintenance effort. Installation requires compatibility with post-mount frame or fork mounts, as well as proper hydraulic system setup procedures. The black finish provides a neutral aesthetic that suits various bike color schemes. This brake set is aimed at riders seeking professional braking performance with the precise engineering of the XTR component group.