Abstract: A base is permanently anchored in a foundation in flush relationship therewith. The base includes threaded openings for receiving one or more threaded fasteners. A ball is attached to one end of a tether having an elastic portion and a nonelastic portion. An L-shaped support for the other end of the tether rotates with respect to a frame mounted on the base. The fasteners connect the frame to the base. The frame holds a vertical sleeve. The support has a vertical arm fitting within the sleeve and extending beyond one end thereof and a horizontal arm with a free end extending beyond the perimeter of the frame. A first projection extends radially outward from the vertical arm adjacent to the one end of the sleeve. A second projection extends axially from the one end of the sleeve to abut the first projection when predetermined limits of relative rotation between the sleeve and arm are reached.