FESTO Pneumatic Exhaust Flow Regulators - GRLA Series. Introducing the GRLA series from FESTO. This range of pneumatic fittings feature exhaust flow regulators. Each flow regulator has an integrated QS push-in fitting. Features and Benefits. One-way flow control function for exhaust air. The one-way flow control valve regulates the piston speed of pneumatic drivers during advance and return strokes The QS push-in fittings and captive seals paired with the robust, metal design enables a reliable and efficient installation that can be rotated or swivelled through 360° axis Simple and fast mounting with QS fittings The pneumatic valves are operated with a screwdriver (slot) Wide operating temperatures Threaded and tube (hose) connection type options can be found within the GRLA series Depending on the choice of valve from the range a precise setting can be obtained. Ranging from slow, medium or fast piston movements