Our Roll Top is the quarter round design. Meaning that it is a quarter of a circle. Two sections back to back would make half a circle. The 12ft Roll Top has an actual length of 11-1/2ft, in order to fit between our standards. The frame of our Roll Tops are made of exterior grade wood, topped with plywood. We cut holes in the ends for handles and easy transport. We keep the amount of wood, on the ground, to a minimum to help reduce ground/rot exposure. As with all of our jumps, we do recommend protecting your Roll Top with a stain or paint treatment.