Flying Diamonds FDX1 Futures Tri Surfboard Fins - Medium/BlackThe FDX 1 thruster is a balanced tri fin template with all around performance. With a neutral template that is not overly upright or raked, its specifically designed to act as a single fin set that can serve as the performance baseline for any shortboard or midlength in your quiver. Built utilizing AirFlex technology with an air core of polyurethane foam, it delivers the lightest possible weight with optimal rebound under load, balancing performance