FCS Q-5XC Glass Flex Surfboard Quad Fin Set. The Q-5XC fins suit performance short boards and guns. Symmetrical rear fins create smoother rail-to-rail transitions in a variety of conditions. Rear fins are asymmetrical side foils (as opposed to center foils) for tighter arcs and pocket surfing. 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. These sizes cater for all surfers in all round conditions. Front: Base: 4.37in. Depth: 4.55in. Area: 14.76sq.in. Rear: Base: 3.86in. Depth: 3.93in. Area: 11.07sq.in.