Specialized valves for precise control of hydraulic fluid flow in hydraulic systems. Includes throttle valves, needle valves, flow control valves, and flow control valves used for speed control of hydraulic cylinders and rotational speed control of hydraulic motors. Essential for controlling arm movement speed in construction machinery, feed rate in machine tools, pressurization speed in press machines, and injection speed in injection molding machines. Unlike pressure control valves and directional control valves, these focus solely on flow control and are selected according to application requirements including unidirectional/bidirectional types and fixed/variable orifice types.