The primary difference between these XTR M9020 Trail Brakes and their Race oriented brethren is the presence of the Servo wave Cam. In the race brakes, Shimano decided the weight savings outweighed the benefit of a tightly controlled braking path, but knew that in downhill, enduro, or trail oriented applications, that super defined path would be a welcome feature for riders who depend on their brakes to keep them out of the trees. At first glance, they don't appear that different from the previous generation, but you can't judge a book by its cover. The caliper and master cylinder are now magnesium, and the levers are carbon fiber. Shimano's also made a number of small improvements to manage heat buildup better, but recommends the new Freeza rotors for maximum performance with these brakes. The new M9020 brake levers are also compatible with the latest generation of Shimano's I Spec design, I Spec II. If you've got a pair of I Spec II shift levers, you can save valuable cockpit real estate by mounting both the shift and brake levers with one clamp.