Girodisc Ferrari 355 Challenge Front RotorsThe Girodisc system is a direct replacement for the OE disc, no modifications are necessary. The disc will bolt directly to the car and work with OE calipers perfectly. 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,