Seac Shuttle short swim fins are made with 100% silicone, designed with two different flexibilities: strength training (Sport version) or cardio training (Power version). Sport version is ideal for beginners especially for muscle strength training or intermediate level swimmers. The swimmer benefits from strengthening the thighs, buttocks, calves and lumbar region, preparing them for more advanced training. Power version is designed for advanced swimmers with long and intensive training sessions, improving kick frequency and cardio resistance. Thanks to the non-deformable silicone structure, Seac Shuttle short fins never lose their shape (memory) and do not get damaged by either pool chlorine or by seawater, making them ideal for snorkeling. The blades dynamics allow the ankles and feet to flex properly, pushing maximum power up through to the fin tips. This design makes the most of the entire surface of the Shuttle swim fins. The Seac Shuttle silicone fins are available both in the Sport and Power versions, with eight sizes from 34 to 46.