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.

Glass Flex has been formulated to replicate the flex and memory properties of hand layed fibreglass. Its advantages over other composite fin materials include stiffness, a more positive flex pattern (nice tip flex, little base flex) and remarkable flex memory. The precision of the injection moulding process ensures the highest accuracy in geometry in each fin produced.
for specific surfboard designs or as specialised fins