The MSV-98322EB is a manual pneumatic directional valve with a three-way operation & three ports (P = Pressure, A = Outlet, EA = Exhaust for port A). Three-way, two-position valves are generally used to fully extend a single acting (spring return) cylinder, or in applications with similar operation. With the detented emergency stop button, air can quickly be applied (and remain applied) to the outlet port until the button is reset.
For more information, please see Data Sheet