Girodisc Front 350mm 2-piece Rotor for Porsche 991.2 C2S/C4S/GTSThe 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. By upgrading your brakes with lightweight high performance replacements as opposed to a big brake kit, your factory bias is maintained as well as your ABS efficiency. The central hat section of our rotor is made from strictly the U. S. sourced 6061 T6 aircraft specification aluminum.