Since 1912, Fulflo has been providing "chatter free" valves that modulate to control pressure: hydraulic bypass relief valves, oilfield valves, pilot valves, pressure regulator valves & hydraulic pressure control valves, which mount in any position. Our hydraulic by-pass relief valves measure from 1/4 - 4". A pioneer in fluid power, we constantly strive to be a worldwide valve producer leader.