Abstract: A coupling for pressurized medium comprising a stud member and a socket member, the stud member and the socket member are mutually locked together in a completely coupled position by a locking ring which engages with circumferential locking ring grooves in the stud and socket member, two sealing rings sealingly engage the stud member and socket member and the stud member and socket member have second grooves into which a safety ring is fitted, the second groove in the socket member has a larger axial extent than the safety ring so that when the locking ring is engaged in the locking ring grooves, the safety ring is not effective to retain the stud and socket members together but is only effective prior to the locking ring engaging the locking ring grooves when the stud and socket members are incompletely coupled together.