Abstract: A hinge positioned at the intermediate extents of the adjacent rail components to hold such components in an aligned orientation including a saddle with a central button aperture, interior plate apertures and exterior end apertures with associated rail pins for pivotally coupling the saddle and the adjacent interior ends of associated rail components, a pair of hinge plates each with a plate pin coupling the upper end of each plate to a plate aperture of the saddle, each plate having an opening extending therethrough, the plates urged away from each other, a liftable block with an elongated slot and with an associated block pin for slidably coupling the block to the saddle, the button having inclined bearing surfaces on their edges and an inwardly facing projection located at the adjacent interior edge of each adjacent rod segment, each projection having an upper curved surface and a lower planar surface receivable by the bearing opening.