The shimano xtr m988 i spec b disc brake and lever set is a fully bled trail brake that use a performance optimized servo wave systems with full adjustability on the fly the oversized 22mm twin ceramic pistons optimised for heat insulation lightweight and stiffness shimano recommend that you use ice tech centre lock rotors for optimum braking performance in a choice of 160 180 and 203 mm as the set doesnt come with the rotor or adaptor this gives you the freedom to use what ever you want