Shimano SM-RT64 rotors offer secure and easy set-up with the proven Center Lock mounting systemPrecision cut stainless steel braking surface improves pad clearing in muddy conditions while aiding cooling under high loadRotor contact surface has been developed for excellent pad clearing and cooling which increases pad performance and lifeAlloy spider supports rotor surface, increasing rigidity and reducing weightRotor houses the magnet necessary for speed sensor function on Shimano STEPS equipped E-bikes allowing frame clearance for wider tyresComes complete with lockring