To adjust resistance, slide the patented cord-lock up the lines to change the shape of the chute. An essential feature for breaking through training plateaus and developing more acceleration, speed, and explosiveness. Parabolic cup shape is sewn right into the chute, giving it instant lift and stability. No more wasted time and effort spent trying to fill the chute with air. Quick-release belt for overspeed training. Rip-stop nylon chute (colors vary). Includes instructions.