FCS MR-TX Glass Flex Surfboard Trailers (2) Fin Set - Natural MR's twin template, FCS advanced foil plus a dynamic stabilizer for maximum performance Advantages over other composite fin materials include stiffness, a more positive flex pattern and remarkable flex memory Glass Flex has been formulated to replicate the flex and memory properties of laminated fiberglass Install this twin fin in your thruster and feel the difference Similar to the TFX, this is the Mark Richards twin fin template in Glass Flex