Feature: The coolant reservoir is attached to the radiator and the engine with hoses and is an important component of the cooling system, which holds the excess coolant fluid used to cool the engine. When a coolant expansion tank has any issues it can lead to issues that: Constantly low on coolant, coolant leaks, engine overheating. This is a non-OEM product, accessory only! Specification: Type: Coolant Radiator Reservoir Tank OE Number:2515000049 Material: PP Color: Black,White Sensor Includes: Yes Position: Front Number of Pins: 2 To Radiator Inlet Outlet Hose Outer Diameter: 17mm / 0.67" To Radiator Outlet Hose Outer Diameter: 27.5mm / 1.08" Suitable for Expansion Tank Cover Diameter:59mm/2.32" Size:24.5x25x22cm / 9.65"x9.84"x8.66"(L*W*H) Fitment: for Mercedes-Benz R320 W251 2007-2009 V6 3.0L Diesel for Mercedes-Benz R350 W251 2010-2013 V6 3.0L Diesel for Mercedes-Benz R350 W251 2006-2013 V6 3.5L Petrol for Mercedes-Benz R500 W251 2006-2007 V8 5.0L Petrol for Mercedes-Benz R550 W251 2008 V8 5.5L Petrol for Mercedes-Benz R63 for AMG W251 2007 V8 6.3L Petrol How to Replace: Turn off and cool down the car, remove the bolts and the reservoir. Allow the remaining coolant to flow back into the drain pan. Replace the new reservoir tank and reinstall the coolant hose to the radiator and tighten the clamp Finally check if function well. Note: Please allow 3-5mm differences due to manual measurement. Package Included: 1 x Coolant Radiator Reservoir Tank 1 × Cap