Shut-off tap for R410A - 5/16" SAE RH female inlet (right) - 5/16" SAE RH male outlet (right) - with depressor.

The shut-off is a service cock for the charge pipe (hose), which allows the maintenance technician to connect to the service connection of the external units (condensers) of the A/C unit systems without causing refrigerant gas and oil leaks during the hooking and unhooking operation.

In other words, thanks to this valve, refrigerant gas leaks into the atmosphere are avoided during maintenance operations on the outdoor unit.