Developed by Sean Mattison for Von Sol surfboards, the FCS VS KNUBSTER is essentially a center 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 center plug to cater for the individual drive requirements of each surfer. The FCS VS KNUBSTER, is 3 3/4” by 2” high. According to Kelly Slater's report, “The KNUBSTER makes your quad set-up feel faster, smoother, and it adds a little more control. It just tightens everything it up a bit”.