Home Fins Technology Contact About Lessacher Duo Weed Double Concave Asymmetrical Windsurfing Fin 100% Carbon Fin sizes (cm): 28 32 36 40 Fin area (cm2): 260 365 440 515 Sail size (m2): 6.5 8.0 9.5 10.5 The Duo weed fins were developed to satisfy the increasing demands of the racing community. They feature a larger surface area and they are already legendary as the first type weed fin that sails upwind and handles just as well as a regular fin. These fins can point remarkably high, which wasn't possible with older weed fins. If you want to do fast runs on a broad reach, this upwind ability is very useful.