The FCS II Reactor Neo Glass Tri Ash - M by FCS is your tight, quick response performance fins, ideal for getting critical and making tight turns. The Reactor is designed for the surfer wanting to get critical and stay tight in the pocket of the wave or perform aerial maneuvers. Good for hollow, punchy beach breaks. Recommended for performance shortboards with a moderate to low rocker. The upright template will also allow your high volume board to pivot more.