FCS PC-7 Tri Fin Set. Resin transfer molding (RTM) allows the Performance Core fins to be made stiffer with the additional benefit of reduced weight. This stiffer flex pattern allows you to push extremely hard through turns while the Inside Foil Technology provides increased drive. Another favorite with the pros, the PC fins will suit the more powerful surfer or those wanting to push each turn to the limit. Base: 4.52" 115.0mm Depth: 4.67" 119.0mm Area: 15.71" 10137mm Sweep: 33°. FCS.