The Bendix 1/4" NPT Inlet Port 175 ± 8 psi ST-3 Safety Valve is designed to automatically release excess air pressure at a preset level and then reset and seal off the system once the pressure drops to a safe level. This valve is made of premium quality materials for durability and long life and features an inlet port of 1/4-18 NPT and a vent of 0.125". It is the perfect solution for ensuring the safety of your system and protecting it from overpressure. FleetPride is your First Click in Heavy Duty®.