An ACDelco Professional, premium aftermarket Engine Coolant Thermostat is a temperature controlled valve located in the engine coolant outlet to, or the inlet from, the radiator, and is a high quality replacement for many vehicles on the road today. It controls the flow of coolant through the radiator to enable the engine to reach and maintain its normal operating temperature. This premium aftermarket replacement engine coolant thermostat is manufactured to meet your expectations for fit, form, and function.