Friction Sway Control uses friction to resist pivotal movement and thereby works against the effects of induced sway. It operates on the principle of "stiffening" the coupling between the tow vehicle and trailer. The degree of "stiffening" or friction is adjusted to suit various trailer weights and towing conditions. Its operation is simple and uncomplicated. It doesn't prevent the generation of sway; it simply works to resist the forces once they have started. * For use with all Class III & IV Hitches * Can be used on left & right side fo trailer