Shimano BR-R8170 Ultegra Flat Mount Disc Brake CalliperHigh power 4 piston brake calliper providing efficient braking with a minimalist design. For use with mineral oil which is non corrosive and less hazardous than conventional hydraulic fluid. The one way internal fluid circuit makes bleeding easy, while great piston retraction increases pad to rotor clearance. Shim less mounting bracket allows for quick installation and set up. Compatible with international standard and post mount forks. To be used in