The 3SW freestyle-wave fin. Developed with help from the Official Test Centre Weymouth. A fin that will give you amazing speed and control, secure and loose carving on the fast flats or choppy waves. The material is K4âs âSuper Stiffâ, the ideal composite for freestyle-wave fins; great reflex, stiff enough for excellent acceleration and direct response, enough flex for speed, grip and control. The 3SW also works great in big wave boards.