1、Can directly replace the broken or shabby one. Reference OEM number is 17138614293. 2、Sophisticated craftsmanship, this coolant expansion tank is perfect to fit for 5 Series F10 F11 520i 528i. 3、The vehicle's engine coolant recovery tank or expansion tank stores excess pressure and coolant when the radiator heats up. The water storage tank helps you keep the radiator full at all times and makes the radiator more efficient. If the coolant is insufficient, it may indicate a leak. 4、Stores and distributors can use pressure testers to check for small, hard‑to‑find leaks in the system. If your recovery tank is damaged, replace it immediately to avoid catastrophic cooling system failure. 5、Processed with high-quality materials of plastic, wear-resistant, high-temperature resistant, and have a long service life.