This is a Genuine Mercedes Windshield Washer Fluid Reservoir Cap, part number 0008691119. It is designed to fit onto the windshield washer fluid reservoir of Mercedes vehicles. The cap helps to securely seal the reservoir, preventing any leakage or contamination of the fluid. It is made of high-quality materials to ensure durability and longevity. This cap is an essential component for maintaining a properly functioning windshield washer system in your Mercedes.