This is a 656 Series Valve Assembly with a 1/2" Line Size, with 3-Way Pilot Valve Action and Flow rate of 2-1/2 Cv. This item can also serve as air station equipment which rapidly responds to large volume demands and supply pressure variations. This pneumatic pilot valve is used in two-pressure systems for either day-night or heat-cool applications. This pilot valve has a 1/2" OD SAE flare inlet/outlet port, 3 to 8 psi pneumatic actuator and a 1/8" NPT female pilot port.