Shimano Deore XT 6-Bolt Ice-Tech Rotor (180mm)
Shimano's XT Ice-Tech rotors use a 3-layer sandwich of steel, aluminum and steel which reduces the temperature of the braking surface. This means quieter braking, and more importantly, less fade on long downhill sections , plus improved pad life. The various sizes give you total freedom of choice over the delicate balance of power versus weight.
6-bolt brake rotors are the most common brake rotor attachemnt. They require six bolts to be torqued in sequence to achive optimum performance.