In pneumatic systems, mechanically and manually operated pneumatic valves are needed to regulate air pressure or compressed air as the medium. Manually operated means that directional control valves are operated (on or off) using a push button, hand lever, rotary lever, mushroom button, or a foot pedal. You can make selections with these valves. You can access 5/2 – 4/2 – 3/2 and 5/3 type valves.