Girodisc Rear 350mm 2-piece Rotor Upgrade for Porsche 991.2 C2S/C4S/GTSThe Girodisc system is a direct replacement for the OE disc with the addition of our provided caliper spacers and longer bolts to accommodate the larger 350mm rotor. The central hat section of our rotor is made from strictly the 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,