For use with Super Hitch Receivers. Designed specifically for truck campers up to 12'. If you have trouble towing with your truck camper because it extends past the end of the truck bed, this is the solution! Select extension by length and weight carrying (WC) or weight distributing (WD) capacity needed. With your truck camper installed, measure from the face of the rear bumper on the truck to the face of the bumper on the camper. When camper is not installed, obtain the overall floor measurement including the rubber bumper on the front and bumper on the rear of camper. Then, deduct the bed length of the truck including the rear bumper.