FCS K2.1 PC Quad Fin Set. Fined tuned and perfected by Kelly Slater himself, this quad setup features Kelly’s signature K2.1 Performance Core fins at the sides and Q-1000 fins at back. The set delivers aggressive drive and hold (for down the line speed/stability) and just the right amount of pivot for tight pocket, performance surfing. Did we mention Slater uses them? Front: Base: 4.33” (110mm), Depth: 4.53”(115mm), Area: 15.23”²(9824mm²) Sweep: 32 degrees, Foil: IFT; Rear: Base: 4.10” (104mm), Depth: 4.26”(108mm), Area: 12.64”²(8158mm²) Sweep: 32.4 degrees, Foil: 80/20. FCS.