The ASCO Joucomatic Series 603 Pressure Detector is a device that is used to measure and monitor pressure in a pneumatic system. It is designed to be placed near the output of the system in cases where the output is remote from the solenoid valve. The Pressure Detector can be used in conjunction with a proportional solenoid valve to provide closed loop control, which allows the system to maintain a constant pressure by adjusting the flow of gas or air into the system based on the pressure reading. The Series 603 Pressure Detector is a useful tool for ensuring that the pressure in a pneumatic system is maintained within a certain range, helping to prevent damage to system components and ensure safe and reliable operation.