These chutes, used throughout the track and field world, are based on the overload principle for building runner's muscle quickness and power. The advantage over weight training is that the chute presents resistance in the actual act of running. Remarkable results have been attained by novice runners. The greatest sprinters and hurdlers also use the chutes regularly. Guaranteed to increase leg speed and Strength. One size fits all. 8 lines for even inflation. Padded belt. Inflates without a wind…All nylon. Includes padded shoulder harness. Storage Bag included.