Abstract: The invention provides for a connection system for structurally connecting horizontal frame members and vertical supports. The system includes connector pairs and supports, frame members and connector pairs for accommodating the frame members and the supports. The connector pair has an axial bore for accommodating a connection screw and the supports include a threaded bushing in the end section for accepting the connection screw. The cylindrical connector pair has notches, adapted to accept the frame members. The cylindrical connector pair includes a plurality of vertical bores circumferencially arranged about the axial bore. The frame members include in the connection section a locking element, the locking element is adapted to fit into one of the bores of the connector pair. The connector pair, the frame members and the supports are structurally connected by tightening connection screw in the threaded bushings.