When you use the resistance chute to exercise, the resistance of the air will produce an backward drag force, so the faster you run, the greater the drag force. This exercise can improve the ability of your acceleration, muscle endurance, and enhance the ability to adjust the direction of the high-speed running. * 48 quot; diameter * 15-20 lbs of resistance * Fits all sizes (up to a 42 quot; waist) * Fully functional unit includes parachute and belt. * Suggestion:long-distance running Package Include: 1* 48 quot; Resistance Parachute