A connector system of a structural frame work for display structures. The system includes a socket device and a plug device that can be coupled to the socket device. The socket device includes an outer housing and a socket member in the socket housing, the socket member having a socket hole of non-circular cross-section disposed in a distance behind a coupling hole that is bordered by a retainer wall of the outer socket housing. The plug device includes a plug body and a coupling sleeve slidably and rotatably fitted onto the plug body that includes an exposed plug end portion axially projecting out of the coupling sleeve to fit into the socket hole of the socket member, the coupling sleeve including at least one radial locking nose projecting outwardly from the free end portion of the coupling sleeve that fits through the coupling hole of the socket housing.
