Oceanic Vortex V-16 Split Fins with Spring Heel Straps * Patented Nature"s Wing Propeller Fin Technology * Composite Material: Blend of Thermal Plastic Rubber (TPR) and Polypropylene * Oversized Side Rails add Rigidity to the Oversized Blades for Increased Lift and Efficiency * Semi-Rigid Battens and Rubber Flex Channels within the Blade