A female connecting device used to accept a male nitrous oxide (N2O) connector to connect two devices together to provide a continuous passageway for the delivery of N2O. It has safety features such as a specific mechanical mating pattern, colour coding and a dedicated tube diameter connection to prevent wrong connection and allow a user to rapidly connect and disconnect N2O dependent devices. It can be attached, e.g., to an N2O regulator or an N2O extension tubing. It can be designed as a diameter-indexed safety system (DISS) connector or a non-interchangeable screw-threaded (NIST) connector. This is not a nitrous oxide terminal unit.