A hinge structure may comprise a first assembly including a central post with an outer surface and a first connector element on the central post for mounting on a first structure, a second assembly pivotally coupled to the first assembly and including a ring extending about the central post, a ring connector connected to the ring, and a second connector element on the ring for mounting on a second structure. A braking element may apply a selectable amount of resistance to pivot movement of the second connector element with respect to the first connector element and including a friction pad extending about a portion of the central post, a pressure band for pressing the friction pad against the central post, and a connecting structure connecting the ends of the band and being adjustable to move the ends closer toward each other and to relax the ends away from each other.