Shimano smrt64 rotors offer secure and easy set up with the proven centre 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 weightcomes complete with steel lockringaverage weight for 160 mm rotor with lockring is 153