FCS VS Knubster Centre Keel Set Fin X Small Red Developed by Sean Mattison for Von Sol surfboards, the FCS VS KNUBSTER is essentially a centre fin that can be added to any quad set-up The fin will increase drive and provide directional control through turns, without sacrificing speed, flow, or the freedom of movement typically associated with a quad. The KNUBSTER is designed with a single tab that allows the fin to be positioned in the forward and rear centre plug to cater for the individual drive requirements of each surfer. Will fit the FCS II Fin System when used with grub screws and the FCS Infill Kit.