Arena's Powerfin Pro II Swim Fins have an innovative design with a sloping surface and hydrodynamic slits in the top to allow you to swim with a faster leg kick and better control. The open heel ensures the best possible ankle flexibility allowing faster upwards motion and a more powerful downward leg kick. Test them out to see how they can help you improve your underwater phase after pushing off the wall. Ideal for advanced swimmers. Faster up-kick, full power on down-kick and more control Inclined short blade for maximum forward thrust and high-frequency kick Special notches on bottom ribs for faster kicks and side rails for better control Customized for left and right foot, with open heels for maximum flexibility