The Nissens Engine Coolant Expansion Tank - 996155 is a product designed for use in vehicles to store and regulate the engine coolant. It is made from durable materials and has a capacity of holding a large amount of coolant. The expansion tank helps to prevent engine overheating by allowing the coolant to expand and contract as needed. It also has a built-in pressure relief valve to maintain the correct pressure in the cooling system. This product is essential for maintaining the proper functioning of a vehicle's engine and ensuring optimal performance.