Flow control or one way flow control valves regulate the piston speed of pneumatic drives during advance and return strokes. This is done through suitable restriction of the flow rate of compressed air in exhaust air or supply air direction. With the one way flow control valve GRLA or GRLZ, the flow control function works in one direction only (exhaust air or supply air), the non-return function works in the opposite direction. With the flow control valve GRLO, the flow control function is active in both directions. Festo Flow Control Valve, One Way, Series: VFOF, QS-8 (Port 1)/G1/4 (Port 2) Port, 2 to 10 bar Pressure, -10 to 60 °C, 590 Lpm Flow Control/310 to 540 Lpm Non-Return Flow Rate, Media: Compressed Air, Brass Trim, NBR Softgoods, 76.8 mm L x 39.5 mm W x 33.8 mm H Dimensions