Shimano's XT Brake Rotor, the SM-RT86, sets itself apart from Shimano's lower-tier offerings through its use of an aluminium core to transfer heat away from the brake calliper.This, combined with the finned heat sinks in Shimano's XT and XTR-level brake pads, combats heat-related brake fade.What that means in trail terms is consistent, reliable braking, even on long, technical descents.