The retaining ring thermostat for Citroën DS is a critical small component that secures the thermostat in place. It ensures that the thermostat functions properly within the car's cooling system, maintaining the engine at the correct temperature. Specifically designed for the iconic Citroën DS, this retaining ring is essential for preserving the reliability and efficiency of the engine's cooling system. Replacing a worn-out retaining ring can prevent overheating and engine damage, extending the vehicle's lifespan. It is a crucial element for any owner wishing to keep their Citroën DS in prime condition.