Aqua Sphere Microfin HP Swim Training Fins has a Rigid sole helping prevent cramping. Closed foot pocket made of durable TPR polymer material. Foot pocket efficiently transfers power from the foot to the fin. Raised rubber ribs allow proper channeling of water Length-calibrated blade allows a consistent kick tempo and increased power. Short blade keeps feet on top of the water. Anti-slip rubber pads grip the wall during flip turns and on wet floor Improves technique while strengthening and toning muscle. Anti-slip rubber pads for gripping the wall during flip turns. The micro fin HP is a great training aid allowing you to power through the water, improving technique while strengthening and toning muscle.