The shimano zee m640 i spec b disc brake and lever set are a fully bled system that use a performance optimized servo wave systems with full adjustability on the fly the 4 ceramic pistons in 2 different diameters optimised for heat distribution and stopping prowess shimano recommend that you use ice tech centre lock rotors for optimum braking performance in a 203 mm diameter as the set doesnt come with the rotor or adaptor this gives you the freedom to use what ever you want to use