arena's unisex Powerfin Pro Training Fins are the swim fins all professional swimmers have been waiting for. Their innovative design features 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. These fins for swimming and training are made of 100% soft silicone material that provides maximum comfort and they are custom designed for the right and left foot. PVC free. Training your legs vertically using Powerfin Pro swim fins for just a few minutes today will help you improve your underwater phase. The vertical leg kick allows you both to control your body position and to make sure you are performing a proper leg kick. Test them out to see how arena's swim fins can help you improve your underwater phase after pushing off the wall. Refer to size chart for the best fit.