The Head's Swim Fin Energy Training Fins are an advanced training fin. It improves technique while strengthening muscle development. The Head team designed an exclusive training fin to assist the development of a powerful kick and stronger propulsion. Fins have a closed foot pocket that assists in a secure & comfortable fit. Fins are made from high grade polypropylene, have a heel pull tab for easy donning and doffing. The Head team designed an exclusive training fin to assist the development of a powerful kick and stronger propulsion. Improves technique and strengthens the muscles. Closed foot pocket for a secure and comfortable fit.