The XDP Coolant Recovery Tank Reservoir Cap XD215 is a direct replacement for the old damaged or leaking cap on your 2003-2016 Ford 6.0L/6.4L/6.7L Powerstroke. Also known as a "Degas Bottle Cap", or "Expansion Tank Cap" this items is often overlooked in preventative maintenance and when it is damaged or fails, it can cause leaks and other cooling system issues.