The Double Up Bar lets you to assemble two C-Tugs together, spreading the load and allowing you to carry even heavier kayaks or boats. The bar is a specific length to keep the wheels close together and allow the double cart to be turned easily. Once loaded and balanced, no lifting is required. All you have to do is pull it. The Double Up Bar works with both the standard C-Tug and the C-Tug SandTrakz carts, which must be purchased separately.