This is the Sherwood Onyx Flex Long Blade Free Diving Spearfishing Fins Features: Extremely soft and comfortable foot pocket. Stiff foot pad carried to the back of the heel for significant energy transfer. Blade channels optimize thrust. Highly flexible and light weight blade. Specifically designed for Free Diving and Spear Fishing. Polypropylene composite blade. The sport of free diving is gaining popularity in the diving community. Freediving products also can be used in many applications for scuba diving as well. The Sherwood Onyx Flex Free Diving Fins are one such product. The Onyx fins are very flexible with tremendous snap in the blade make them very popular among free divers, however these same fins can be used with scuba equipment. The longer blades provide additional power and leverage for the diver with or without a cylinder on her back.