FCS Knubster Centre KeelCan be added to any quad set up. Increase drive and provide directional control through turns. 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