A male connecting device used to connect to a medical gas pipeline system or other gas source allowing a user to rapidly connect and disconnect helium/oxygen dependent devices to a mixture of 79% helium (He) and 21% oxygen (O2) supply. It has safety features such as a specific mechanical mating pattern, colour coding and a dedicated tube diameter connection to prevent wrong connection. It is used to connect into an helium/oxygen terminal unit or female connector. It can be designed as a diameter-indexed safety system (DISS) connector or a non-interchangeable screw-threaded (NIST) connector.