FCS2 Quad Rear Fins - Left and Right Set Please refer to the photos for the size. These are rear fins, slightly smaller than a size M thruster fin. Price negotiable for those purchasing with thruster fins. * Size: M * Color: Black * Material: Engineering grade polymer, Glass Flex * Designed for a balance of speed, flow, and response * Ideal for surfers looking for an all-around fin * Offers a combination of speed and maneuverability.