These are a set of CNC machined billet aluminum bumper bars that can be used on your existing wheelie bars. They are 6 inches tall in the back to pass most clubs rules. These are fully adjustable to allow the back part to be 90 degrees with the ground. They pivot on the wheelie bar bolt. You will have to drill one hole in your wheelie bar after you have them set where you want them. The 1/4 thick ones are milled 1/8 deep and the 3/8 ones are milled 3/16 deep, so when put together they fit nice on the wheelie bar.