This classic Weight Distribution kit comes equipped with all you need to restore natural balance of your tow vehicle, suspension and steering geometry. Suitable for ball weights between 135 kg and 275 kg, the 600 lb classic Weight Distribution kit comes with trunnion style spring bars that are ideal for trailers and caravans that have a 4 inch A-frame, with the coupling mounted on the top, or with a 5inch and 6inch A-frame, with the coupling mounted on the bottom.