Genuine OEM Volkswagen Brake Master Cylinder, part number 3D0611021. This critical component converts the mechanical force from the brake pedal into hydraulic pressure, which is then transmitted to the wheel brakes. Constructed from durable metal and weighing 0.65 kg, it is essential for the vehicle's braking system. Using a genuine OEM master cylinder ensures precise hydraulic pressure generation, reliable sealing, and long-term performance, which is paramount for braking safety and effectiveness.