StopTech High-Performance Replacement Left Side Slotted AeroRotor (380x35mm). This is a premium replacement rotor ring designed specifically for StopTech Big Brake Kits (BBK). The patented AeroRotor design optimizes airflow and cooling capacity through unique internal vane geometry, significantly reducing brake fade and extending component life under high-performance driving conditions. The slotted surface helps clear debris and gasses for consistent pad contact. The package includes: 1x Replacement Rotor Ring (31.846.1101.99), 1x Mounting Hardware Kit (including 10 drive pins, 10 washers, and 10 nuts for 2-piece rotor assembly).