Genuine OEM Land Rover Expansion Tank Cap, part number LR000243. This cap seals the cooling system, maintaining the necessary pressure to prevent coolant boil-over and ensure efficient engine cooling. It is typically located on the coolant expansion tank. The cap is rated for 145 kPa (21 psi) pressure. Choosing a genuine OEM cap ensures the correct pressure rating and reliable sealing, preventing leaks and maintaining optimal cooling system performance.