Genuine OEM Mercedes-Benz Coolant Reservoir Cap, part number A0005019915. This cap seals the engine coolant reservoir and maintains system pressure for optimal cooling. The cap measures 0.07m in length, 0.03m in width, and 0.07m in height, weighing 0.05 kg. Genuine OEM caps are manufactured to precise specifications to ensure a proper seal and maintain the correct system pressure.