 Kelly Slater designed the K2-1 fins to be more maneuverable and faster off the top than the original K-fin. The larger, more upright side fins have greater flex for tighter turns and faster turns. The smaller, stiffer center fin adds control. They are Kelly's world-winning template, ideal for high-performance surfing. You have to add the K2-1 fins to your quiver if you don't have them yet.