The MORryde RPB72-VL-04 Pin Box System - 11,501 - 14,000 GVWR will deal with rough towing and road shock by using an exclusive rubber shear spring. The horizontal planar motion of the rubber spring absorbs towing shock of road abnormalities. By diminishing transfer forces from the trailer to truck, your ride quality will significantly and noticeably improve giving a softer and more comfortable ride while towing your fifth wheel. The Pin Box System can be installed on most fifth wheel trailers. Ordering a MORryde Pin Box System requires knowing GVWR of the trailer, and the part number of the stock pin box (usually found on a label on the pin box). Reference the chart in additional product information to determine which pin box system is right for you.