The FCS II Reactor PC Carbon Quad-Rear Surfboard Fin is a high performance surf fin made from Preformance Core Carbon material. The FCS II Reactor PC Carbon Quad-Rear Surfboard Fin is recommended for performance shortboards with moderate-to-low rocker and surfed in hollow, fast, waves and punchy beach breaks. A more advanced fin, the FCS II Reactor PC Carbon Quad-Rear uses an upright template with flat foils on the side fins to allow for acute directional changes. In other words the FCS II Reactor PC Carbon Quad-Rear is designed for surfers who like to stay tight in the pocket and perform tight, quick turns, and aerial maneuvers. *Please Note: this fin is designed to be used exclusively with the FCS II Fin System, and will not fit in the traditional FCS Dual Plug System.