The Aquafins Aquatic Exercise Kit tones and strengthens the legs, lower back, inner and outer thighs, arms, chest, and upper back. Aquafins, which use surface area and drag to create force and resistance, make an excellent addition to exercise or rehab underwater workouts. The water therapy exercise equipment fins are made with Santoprene rubber. Each Aquafins Aquatic Exercise Kit includes 2 cuffs, 4 predator fins, and a mesh carrying case.