Sram guide r disc brakewhats it going to take to ride that line its steep its rocky youve passed it a hundred times but not this time with the all new sram guide r you have the power proven 4 piston calipers give you smooth one finger control features like reach adjust let you dial it in just right and guide perfectly complements other sram components and gives you flawless performance on every ride featuresweight 375glever material aluminumcaliper design 4 piston dual diameter