Generic RED-6X4 Reducing union push-in pneumatic fitting, joins 6 mm tube to 4 mm tube. Used to neck down from a manifold supply to a branch line. Festo QSM-MSL / SMC KQ2R / Camozzi 6580 equivalent. Used in pneumatic control and actuation lines feeding cylinders, valves and industrial automation cells at 4-10 bar working pressure.