Valves that control the flow rate, pressure, and direction of hydraulic fluid in hydraulic systems. Includes relief valves, check valves, directional control valves, flow control valves, and pressure control valves, used in hydraulic circuits of construction machinery, machine tools, press machines, injection molding machines, etc. Classified by operation methods such as solenoid valves, pilot valves, and manual valves, these are critical components that ensure system safety and efficiency.