Check the listing for details. FCS II Reactor Performance Core Tri Fin Set - Charcoal / Black - S - New. Condition: New. Listed at 110.00 USD. About Us | Contact Us Boardshorts Rash Guards Sandals Hats T-Shirts FCS II Reactor Performance Core Tri Fin Set - Charcoal / Black - S - New Item Details We are an authorized dealer for every item we carry. In every case, we buy directly from the manufacturer or from an authorized distributor. If you would like more detail regarding the source of this product, do not hesitate to contact us. The FCS II Reactor fin is a fast reacting fin for performing tight radius turns. Designed for surfers who like to stay tight in the pocket and perform aerial maneuvers. 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.Performance Core fins are resin transfer molded with fiberglass and resin around a hex core. Intermediate response. 55% glass.