They are used in all those situations where the full flow in one way and the stop on the opposite way is needed. The sizes are from 1/8 BSPP (1(8 G) to 2 BSPP (2 G). This male/female check valve has been designed to eliminate one of the two connecting fittings, with the aim to better rationalize the application. The external body is made by high resistance steel and externally protected from oxidations by zinc treatment. On request we can supply a zinc/nickel treatment to increase the oxidation resistance when the valve is located in external environments. Different opening than the standard one (1 bar) are available: 3-4.5-6 bar.