Genuine OEM Volkswagen Brake Fluid Reservoir, part number 1K1611301D. This reservoir stores brake fluid for the hydraulic braking system, ensuring sufficient fluid for operation. It is located at position 3 in the diagram. The part weighs 0.266 kg and has dimensions of 0.14 m x 0.12 m x 0.15 m. Genuine OEM brake fluid reservoirs are manufactured to exact specifications to prevent leaks and ensure proper brake system function.