FCS GS Trailer Fin Natural Glass Flex Center The FCS GS Trailer fin is a single trailer fin that loosens up on the tail of any board, and is an ideal compliment to a fish or twin set-up The GS Trailer fins have an 80/20 Foil Glass Flex is the FCS material formulation created to capture the flex and memory properties of laminated fiberglass in a fin that is manufactured using injection molding techniques By using injection molding, FCS can create complex templates with precision and ensure consistent quality in every fin It`s also least expensive way to manufacture fins so the prices reflect that