Genuine OEM Mercedes-Benz Master Brake Cylinder, part number A0004317501. This master cylinder is a critical component of the vehicle's hydraulic braking system, responsible for converting the driver's foot pressure on the brake pedal into hydraulic pressure that actuates the brakes. It is typically mounted on the brake booster. The part is made from robust materials to withstand high pressures and ensure durability. Genuine OEM master brake cylinders are vital for maintaining the precise hydraulic balance and responsiveness required for safe and effective braking.