Ceramic plates form a longer-lasting seal against oil and dust than rubber seals that deteriorate over time. These valves withstand use in corrosive, dusty, and dirty environments such as foundries, paper mills, and steel plants. Often used to extend and then retract a cylinder at different speeds, they create two actions and have two exhaust ports, which allows you to control the speed of each action by attaching a flow control valve to each exhaust port. Apply voltage to the electrical connection to actuate. They direct airflow from the inlet to your equipment and exhaust return airflow to create motion. Also known as 4-way valves.