CURT A-Series 5th Wheel Wedge Kit for Rotating Pin Box Model 16992CURT A Series 5th Wheel Wedge Kit for Rotating Pin Box Model 16992 A CURT 5th wheel wedge is a simple but reliable way to allow a CURT 5th wheel hitch to be used with a rotating 5th wheel pin box. A pin box mounts on top of the 5th wheel head and provides a new pivot point for the kingpin and wider turn radius for the 5th wheel trailer. To keep the pin box from swiveling in its 5th wheel mounting location, a 5th wheel wedge inserts into the hitch