Solenoid valves enable proportional flow control to actuators so that operators can control their speed and direction of motion. Inside, spools move in response to electrical pulse-width-modulated (PWM) signals so that more or less fluid flows through them. But to ensure high accuracy, spools should be made out of materials that will not expand in humid environments. And as protocols for wireless controls change, signals sent to solenoid valves should be translated from signals sent by Ethernet or PLCs. Here are a few solenoid valves with features that benefit a range of hydraulic systems used today.