This product features a combined needle and check valve flow control that enables you to control the air flow from air cylinders thus controlling the piston strokes speed, while extending or retracting, depending on their circuit location. The J-Series Flow Control Valves allow one direction free flow where in the opposite direction, the needle valve meters the flow. On the chart are models listed having either a 1/4"NPT(JFC-4) or 3/8"NPT(JFC-5) male threaded outlets,a recessed screwdriver slot(R) or knurled knob(K) flow adjustment needles and female NPT Push-Quick inlets. A 1/4" Push-Quick fitting is featured in P08 models and 3/8" Push-Quick fitting for the P12.