FCS II Reactor Performance Core Quad Rear FinsSpeed & tight turns. Ideal for beach breaks. Overview Designed for speed and tight turns, with added tail release. Upright template allows for tighter, more acute directional changes. Smaller centre fin for increased pivot and tail release. Ideal for surfers who like to perform fast, progressive turns. Quad Rear (2 fin) set. Ideal Conditions Suitable for hollow waves, particularly good for beach breaks. Board Types Designed to fit the FCS II Fin