Shimano XT M8120 4-Piston Disc Brakes from BikeBling.com
Amazon.com: SHIMANO Deore XT BL-M8100/BR-M8120 Disc Brake and Lever - Front, Hydraulic, Post Mount, 4-Piston, Finned Metal Pads, Black : Sports & Outdoors
SHIMANO XT BR-M8020 4 Piston Disc Brake One Color, Front : Amazon.sg: Sporting Goods