A NAMUR solenoid valve is directly mounted to pneumatic actuator inlet/outlet ports.

The function of a NAMUR solenoid valve is to control media flow: the valve itself is controlled by an electric solenoid, which opens or closes the valve, by controlling the amount of air thru a pilot to the pneumatic actuator. The solenoid and actuator work in tandem to control flow speed, flow amount, and flow direction.  Likewise, the valve is operated in either the normally closed, or normally open position.
Solenoid valves are available in several configurations, including 3 way and 4 way. They are commonly applied for operating double acting rack and pinion actuators.