Girodisc McLaren MP4-12C Front Rotors, incl. spacersThe Girodisc system is a direct replacement for the OE disc on all vehicles that came equipped with cast iron rotors from the factory. Our rotors are slightly larger than the 370mm OEM rotors at 380mm and come with caliper spacers to accommodate the larger rotors. The central hat section of the disc is made from 6061 T6 aircraft specification aluminum. The disc is made from cast iron to the same specification and material as used by professional