The Solla combines TUSA&';s rich history of performance fin design with the latest advanced materials and hydrodynamic innovations. The Solla has several unique features that deliver superior propulsion, speed and maneuverability. The Universal Bungee Strap is adjustable, and one-size fits all. It&';s comfort-flex hinge, and rubber heel cup with a finger loop make for an easy fit. All of the same great features of the original Solla updated with a comfortable Bungee Strap ForceElast structure with dual ribs for optimum propulsion. Concave shape at the tip of the blade that stabilizes the water flow with the smooth blade. Stiffer material on the top of the toe and bottom of the heel to reduce power loss when kicking