Shimano XTR BR-M9120 Disc Brake Caliper - Front Rear Post Mount 4-Piston Includes Finned Metallic PadsShimano XTR BR M9120 Disc Brake Caliper Front or Rear Post Mount 4 Piston Includes Finned Metallic Pads. The XTR M9120 caliper features a MONO BODY design which is machined from a single cold forged block to maximize rigidity and four ceramic pistons for perfect Rider Tuned stopping power. Higher braking force with reduced input force at finger tips delivers a high linear response and braking power stroke Time lag reduced by 30% compared with BR M9000