The Speeder HD is suitable for the more trained athletes. The Speeder HD fin is the result of a careful research into the dynamics of movement. The innovative foot pocket is reinforced with a rigid insole placed under the sole of the foot; this allows optimal energy transfer during finning. 29-degree angle, rigid insole and side spars that turn under the sole of the foot give the foot pocket an unparalleled mechanical structure but above all the possibility of using even very soft rubbers for exceptional comfort. During the development phase, in addition to paying particular attention to the characteristics of the two components that make up a fin, foot pocket and blade, we implemented the interaction between them through the improvement of the coupling system, effectively improving the overall functionality of the product. The molded polypropylene blade ensures better propulsive thrust and excellent springback while minimising the finning effort. The blade has been made with a differentiated thickness: the heel has a thickness of 3,5mm, the toe has a thickness of 1,8mm