Those couplings are used for potable water, lavatory, air start, APU, engine oil and preconditioned air components.
COUPLING - OXYGEN QUICK DISCONNECT COUPLING - OXYGEN QUICK DISCONNECT
COUPLING-OXYGEN QUICK DISCONNECT COUPLING-OXYGEN QUICK DISCONNECT
Airbus Skydrol Service Coupling. Airbus Skydrol Service Coupling.
Boeing Skydrol Service Coupling. Boeing Skydrol Service Coupling.
CSD/APU Fill & Overfill Service Coupling CSD/APU Fill & Overfill Service Coupling