The Shimano XT Ice Tech SM-RT86 6-bolt disc rotor uses high-tech construction and design to reduce heat and improve braking response. Features Ice Tech design offers advanced heat control for disc brake systems: the outer layers of the rotor are made of stainless steel, which are bonded to an aluminum core This design captures the best of both worlds: the durability and powerful braking response of stainless steel along with the light weight and heat dissipation of aluminum Plus, the strong aluminum spider dissipates even more heat and adds rigidity Lower rotor operating temperatures means less power fade and improved brake pad longevity The Shimano XT Ice Tech SM-RT86 6-bolt disc rotor is available in 160mm or 180mm sizes; sold as individual rotor and not compatible with Center Lock hubs If your new rotors are a different size than the ones you&';re replacing, then you&';ll need new brake adapters! Check out our guide to getting the right brake adapters to spend less time on the computer and more on the trails.