Self-sealing couplings have been mounted in the manifold and accessory ports which open automatically when the two members are brought together. However, these couplings are so constructed that the ports on the manifold and accessory members must be substantially perfectly aligned in order for the couplings to open properly. Thus, extremely close tolerances are required for the manufacture of the manifold and accessory ports, increasing the cost of fabrication. The self- sealing coupling is in the form of two cartridges which are mountable in the manifold and accessory port members. Each cartridge has a housing which carries a rock able ball segment body. A self- sealing valve is mounted in each body, the construction being such that the valves will open when the port members are brought together. The rock able ball segment bodies will permit proper engagement of the coupling halves even though there is some misalignment between the ports themselves. In a self-sealing coupling (fluid) for connecting two members having ports which may not be exactly aligned, first and second cartridges, each cartridge having a housing mounted in one of the members in alignment with the port thereof, bodies mounted in the housings and having ball segment portions which permit limited rocking movement of the bodies with respect to the housings, means retaining the bodies in the housings, valves mounted in the bodies and connected to the ports whereby the valves are normally held in closed position by fluid pressure, and inter engaging surfaces on the valves and bodies responsive to the mating of the cartridges to open the valves, thereby permitting fluid flow between the ports, the ball segments permitting the inter engaging surfaces to be properly aligned despite misalignment of the ports.