The AU 24K Side-bites offer a reinforced blend of carbon fiber in the lower half of the fin that deflects energy from the solid base to the flexible tip. This energy has a recoil effect when combined with our patented AU signature curve! It creates what we refer to as "Spiral Propulsion Technology". This fin set offers a great deal of control and drive to any 2:1 longboard/retro board, SUP & Wakesurf set-ups. WAU created the AU 24K Side-bites after popular demand and incredible testimonials of how much more they improved the ride of the above-mentioned wave riding choices.