Girodisc Porsche 992 GT3, GT4 RS Rear RotorsThe Girodisc system is a direct replacement for the OE disc on the 992 GT3 with OEM iron rotors. No modifications are necessary, and it allows the use of unmodified factory pads. The disc will bolt directly to the car and work with factory calipers. The central hat section of our rotor is made from strictly U. S. sourced 6061 T6 aircraft specification aluminum. The disc is made from our own proprietary cast iron, poured in the USA and machined from