... valves permit airflow in one direction. Used for maintaining the output pressure at a constant lev quick push-in fitting -check ... , air fittings, one touch tube fittings, push in fittings, plastic push in fittings, air hose fittings, air tube fittings, ... fittings.Features:The check valves permit the airlow in one direction but stops in the reverse direction.The check valves works at the pressure of ...