Thermal relief valve, 1/4 inch NPT male thread, 43mm in length. Max. inlet pressure of pumps is 200 PSI. It can protect pressure washer pumps operating in a safe temperature range to prevent overheating. Brass construction ensures nice durability to withstand high pressure and different weather conditions. Replacement parts for pressure washer, makes pressure washing easier. Not easy to rust, easy to connect, durable in use. When water temperature reaches above 145º F, pump seals may fail. It will open to release hot water and allow cold water to enter the pump. So it continues to operate at a safe temperature. If the pump have ever overheated, the thermal relief valve must be replaced. Thread Size 1/4 Inch NPT Overall Length 43mm Mate.