Girodisc Porsche GT2 RS Clubsport Front RotorsThe Girodisc system is a direct replacement for the original disc, no modifications are necessary. 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 start to finish in house at Girodisc. The rotor utilizes a curved vane design, developed in racing to act as a centrifugal pump to force cooling air