Features: 1.OEM numbers for reference: 17111436381, fit for 5 Series E39 520?530/7 Series E38 728. 2.Engine coolant recovery tank, used to store excess pressure and coolant as the radiator heats up. 3.The reservoir helps to keep the radiator full at all times and makes the radiator more efficient. 4.Original standard, direct replacement for the old or broken coolant expansion tank. 5.The installation is simple, does not require complicated operations and tools. Specification: Item Type: Coolant Expansion Tank _x000D_ Material: Plastic_x000D_ OEM: 17111436381_x000D_ Fitment: _x000D_ Fit for 5 Series E39 520-530 _x000D_ Fit for 7 Series E38 728_x000D_ _x000D_ Instruction:_x000D_ If your coolant is low, it may indicate a leaks. Shops and dealers can use a pressure tester to check the system for smaller hard to find leaks. If your recovery tank is damaged, replace it immediately to avoid a catastrophic cooling system failure. Note: Please double check the part number of your item, matching information is for reference only. If you are unsure of the item, please contact us before buying to avoid unnecessary return, thanks!