Fin with foot pockets made from thermo-rubber in two different hardnesses in order to combine the best in comfort and performance. The green sections have a stiffness of just 40 shore hardness, offering a soft and comfortable contact with the ankle and toes. The black sections have a stiffness of 90 shore hardness, able to transmit power without dispersion. The Spitfire features anti slip patterns on the heel. The detachable blade has 2 water rails to eliminate skidding and greatly improve performance. The Kelp blade has a 15% softer response then the Spitfire black and features a keyhole in the blade area decreasing water resistance and reducing side to side slipping. Features and Benefits Dual hardness foot pocket Water rail system Anti-slip pattern on heel Available in: transparent green Specifications Blade Material: Polypropylene Blade Length: 59.4 cm (23.4 inches) Blade Angle: 22 degrees