Back to the FUTURE Made with similar outlines of our late 70's and early 80's twin fins, the TWINNY has many up grade features, a slight roll on the bottom chest area smoothly transitioning into a more defined paneled concave. Our tucked edge that feathers out 1/3 of the way up the tail of the board maintains that the water will be release quickly giving the rider an accelerated drive off the bottom and through flat sections of the wave. Stock: Hard wing Swallow. Twin Fin (back trail fin available.) Single to concave VEE off tail.