AiRotor technology taken to the limit. No other composite rotor comes even close. Lightest Disk on the market! Braking Annulus: High grade SUS410 stainless steel. Ground and Hardened to 47 HRC. Spider: Aero grade 7075-T6 heat treated alloy. Exceptional Heat Dissipation from the braking annulus, due to high thermal conduction of the spider. Fully Tested-Beyond all Standards.