Genuine OEM Volkswagen Vented Brake Disc, part number 4M0615301BM. This disc rotates with the wheel and is gripped by the brake pads to slow the vehicle. It is positioned as item 5 in the brake assembly diagram. This brake disc weighs 17 kg and has a diameter of 0.46 m. Genuine OEM brake discs are critical for ensuring consistent braking performance, proper heat dissipation, and a long service life due to their precise material composition and manufacturing tolerances.