IST Bora Bora Scuba Diving and Spearfishing Fins (Black, S/M)A powerful fin by nature. Its rigid, robust blade is delicately balanced by the special elastic centre membrane, which is designed to channel water backward, giving more speed and power to get on top of the conditions. The angle of the blade in relation to the foot pocket is designed with efficiency in mind. As each stroke begins, the fin provides ample propulsion without straining the muscles. Rubber grip under foot pocket prevents slipping on deck