Hope's Floating Disc Rotors are a great choice for riders seeking excellent performance out of their brakes. The floating rotor design allows for better heat management due to the steel braking surface being riveted to an aluminum central carrier. When the outer rotor is subjected to serious heat, it expands. By allowing it to float separately from the center, it is free to expand and shrink at will without putting any stress on the carrier and prevent warping. Includes rotor bolts. Braking surface is measured at 1.8mm thick. If the amount of play exceeds 1mm, they should be replaced.