Expansion tank and overflow reservoir that helps keep your engine at the right temperature under a variety of conditions, acting as a dedicated coolant reservoir. Durable plastic construction designed to withstand underhood heat and engine vibration for reliable performance. Easy installation using the original hardware; plugs into the vehicle for a straightforward replacement. Professionally manufactured to ensure dependable operation and long service life. Compatibility and fit: designed to standard radiator coolant reservoirs that use the original hardware, compatible with vehicles that require a radiator expansion tank. Use scenarios Replacing a worn, cracked, or leaking coolant reservoir in a passenger car or light truck. During cooling system service such as a coolant flush or radiator replacement to restore proper reservoir function. In hot climates or for vehicles under heavy driving load where consistent temperature management and coolant expansion control are important.