Flow Control or Throttle Valves
Controls the flow passing through the valve.
Generally a sharp edged orifice or other restrictor.
Fixed or variable - fixed orifii provide constant flow or adjustable provide variable flow.
Pressure compensation - Without pressure compensation the flow will vary with changes in pressure either side of the orifice.
Often come with in-build check valves to control flow in one direction only.
Flow control accuracy can vary widely between valves.