The GiroDisc 2-Piece Slotted Performance Brake Rotors replace the OE (Original Equipment) brake disc, requiring no alterations. The disc fits OE calipers and bolts straight to the vehicle. Your factory bias and ABS efficiency are maintained by replacing your brakes with lightweight, high-performance alternatives rather than a larger brake kit. Girodisc rear rotors weigh 11lbs vs. 18lbs for stock. Reduced rotational and unsprung weight improves acceleration and suspension response. Our rotor's center hat is crafted from U.S.-sourced 6061-T6 aluminum. The disc is built from Girodisc's unique cast iron and machined in-house. The rotor uses a racing-inspired curved vane design to drive cooled air across the disc.