Cressi s most technically advanced fin, the Reaction uses a completely new polypropylene blade material that is more reactive, flexible and trim than previous designs. It kicks easily yet powerfully and is suitable for divers of every experience level. The new, longer blade efficiently transfers energy from the computer-designed foot pocket, and like other Cressi fins, the blade extends from the top of the foot pocket to maximize its effective surface area for more thrust. Other innovations include new locking strap buckles and no-slip material for better traction out of the water.